# Drive by Wire & Sprint Booster Product?



## Arnolds64 (Nov 13, 2009)

Does the Drive by Wire Sprint Booster help with momentary lag between gears with our 225 cars? Does it do what it says in regard to our Drive by wire slow signal?


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## PLAYED TT (Oct 17, 2010)

What lag?:laugh:


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## The_RoadWarrior (Nov 21, 2011)

I heard it works great from real users and the concept makes sense in theory. I have not personally drove a car with one so I can't say for sure. 

The delay between gas pedal application and actual throttle response is marginal and can be ignored in normal driving. However is becomes annoying in Motorsport situations where on/off throttle and pedal modulation is critical to performance ( feels like wearing a condom on your right foot ).


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## PLAYED TT (Oct 17, 2010)

I have a wotbox and I can't tell.


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## 20v master (May 7, 2009)

There is no "slow signal," you just have an inefficient charge piping setup, especially if it's all stock.  And no, this thing is a gimmick.


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## PLAYED TT (Oct 17, 2010)

That's what I was thinking


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## Audiguy84 (Nov 14, 2006)

20v master said:


> There is no "slow signal," you just have an inefficient charge piping setup, especially if it's all stock.  And no, this thing is a gimmick.


agreed, electricity, moves at the speed of light, is that not fast enough


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## PLAYED TT (Oct 17, 2010)

I can haz faster plz?


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## ManOfManyGTs (Dec 11, 2007)

This product has been the topic of much debate: how it works, what it actually does, and why you need it. I can tell you that it does do SOMETHING.

My dad has a 05 S4 and he put one on his car. The difference was huge. In "green" mode (sport), it had much quicker throttle response, had better response from the pedal sooner, and really improved the drivability of the car. In "red" mode (race) mode it was absolutely insane and down right dangerous on the street. As soon as you tapped the throttle, the car took off like a rocket ship.

Again, not on a 1.8t and take it for what its worth, but I really liked what it did for the s4 in the REAL world (where it counts), all the nay saying and technical jargon aside. 

I find that most of the people who talk crap about sprint boosters have never driven a car with it installed. I'd advise doing a trial or finding someone with one and driving it to get your own impressions. The way I see it, its another tool for tuning; if you like what it does for your car keep it, if not, leave it.


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## The_RoadWarrior (Nov 21, 2011)

Audiguy84 said:


> agreed, electricity, moves at the speed of light, is that not fast enough


The same logic applies to the haldex too right? Or it's a double standard? 
We all know that a DBW can be made to be as quick as can be but is that the case here with our cars?

There are maps that control the ramp of the signal from calculated torque request (gas pedal angle in relation to how fast you press it) to actual reaction of the electronically controlled throttle plate. The reaction is gradual and linear at best (go drive dbw Toyota and you will understand how quick dbw can be) and can be tuned/altered just like the ecu or haldex controller.

The only thing I see wrong with the sprint booster is that it is only piggybacking the signal and not really changing the actual ramp map. Oh also that the person who wrote the technical specs on their website is mentally challenged.

People with MAF controlled water injection that installed this had to reset their spray onset because the MAF voltage was so much higher and quicker that they were spraying prematurely.


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## 1fast2liter (Apr 4, 2005)

The_RoadWarrior said:


> The same logic applies to the haldex too right? Or it's a double standard?
> We all know that a DBW can be made to be as quick as can be but is that the case here with our cars?
> 
> There are maps that control the ramp of the signal from calculated torque request (gas pedal angle in relation to how fast you press it) to actual reaction of the electronically controlled throttle plate. The reaction is gradual and linear at best (go drive dbw Toyota and you will understand how quick dbw can be) and can be tuned/altered just like the ecu or haldex controller.
> ...


is that like premature..........lol you get my drift...lol ahigher maf signal sooner wouldnt that be bad in relation to the actuall throttle position?


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## 20v master (May 7, 2009)

Unbolt your throttle body and set it on the intake manifold plenum where you can see the throttle plate through the gap between the hood and the cowl with the hood raised. Turn igntion to on without starting, and press the gas pedal. Tell me what delay you see. The OEM programming opens the throttle 100% when the gas pedal is over ~75% anyways. I don't think this is affected by rpm. Max, is said Toyota a turbo car or N/A?


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## The_RoadWarrior (Nov 21, 2011)

20v master said:


> Unbolt your throttle body and set it on the intake manifold plenum where you can see the throttle plate through the gap between the hood and the cowl with the hood raised. Turn igntion to on without starting, and press the gas pedal. Tell me what delay you see. The OEM programming opens the throttle 100% when the gas pedal is over ~75% anyways. I don't think this is affected by rpm. Max, is said Toyota a turbo car or N/A?


I think you are missing the point Adam. It's not really about how much the throttle plate is openned but the ramping rate at which the calculated torque request (Gas pedal angle vs a host of other parameters) is transferred into throttle angle. It can be gradual and linear like ours or more aggressively mapped.

I have seen the ramping map for our car before (wished I had saved it for future references) and it is not spectacular and can be pepped up.

Look at our ECU hierarchy of commands, the calculated torque request (aka gas pedal) is all the way on the left - from that, the demand signal goes to the upper priority scheduler than a first target conversion map and then a second conversion map (the one I believe the sprint booster is piggybacking) before finally getting to the *Throttle angle duty*
Any change to the two maps on the left of the throttle angle will alter its behavior ( the one closest to it is better because it does not affect others things that are derived from it)


Uploaded with ImageShack.us


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## 20v master (May 7, 2009)

The_RoadWarrior said:


> I think you are missing the point Adam. It's not really about how much the throttle plate is openned but the ramping rate at which the calculated torque request (Gas pedal angle vs a host of other parameters) is transferred into throttle angle. It can be gradual and linear like ours or more aggressively mapped.


You're implying that the ramp up could be so slow that the throttle would be "lagging" the actual pedal. I think that's the point you're trying to make. Have you observed the throttle plate in the manner I described? There's a reason TIP, intake, intake manifold, throttle body, etc, all get reviews of "helping throttle response." You know the system is inefficient with it's number of transitions, reductions, twists and turns, and even deleted an IC yourself for the pressure drop reduction. This "ramp up" rate of throttle plate opening you are describing doesn't make sense (to me), as it implies that the ECU would open the plate slower than the pedal inputs to produce torque, which would do nothing but delay the torque delivery vs requested, which according to the logic being used, would likely invoke MORE throttle opening to get to requested torque quicker (which is why the plate opens 100% at 75% of throttle input anyways). The throttle is a linear voltage input, and the pedal output is the same. Yes there is logic between, but I doubt it's anything put a proportional or differential alogrithm. If I'm off base, please educate me.


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## The_RoadWarrior (Nov 21, 2011)

20v master said:


> The throttle is a linear voltage input, and the pedal output is the same. Yes there is logic between, but I doubt it's anything put a proportional or differential alogrithm. If I'm off base, please educate me.


You are not totally off base and I am in agreement with everything else you said. What you're missing is how the inputs are transferred from pedal to motorized throttle plate. The ME7 is a torque based ECU and use calculated request ( calculation of how much torque is requested by the driver through pedal angle vs other sensors inputs). The way the driver's input ( gas pedal angle) is processed and transferred into the throttle plate is not always a 1:1 ratio and the engineers purposely made it gradual for better drivability. There is definitely a delay between request and actual depending on the conditions and it can even be logged if needed ( that is also implying that sometimes there is no difference between the two, but not when it's most needed at early pedal angle). 

I have done your suggested experiment before when testing the rumored theory that you can press the pedal too far and need to modify the pedal stopper (supposedly, exceeding the 100% request range, forces less than 100% actual throttle angle as a result. The proponents of this theory add extra pedal stopper length to stop the request to fall outside of that 75-100% pedal angle). That experiment clearly can not accurately measure the ramp rate between input and throttle angle except in that 75-100% range. It is the early pedal angle that has the most delay through mapping and where you will get any kind of improvement (not 100% pedal angle when there is no mapped differential).


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## The_RoadWarrior (Nov 21, 2011)

Still haven't found the specific maps that deals with the ramping rate but found some good literature on the subject written by someone that knows the system. A lot more detailed and sound explanation than my previous attempts (good read for anyone interested in learning how these cars work and make power). Enjoy  !

* "The Bosch ME-Motronic system takes a radically different approach to previous engine management systems. While at first it appears little different to any electronic management system - fuel injectors, input sensors, an Electronic Control Unit and so on - the use of accelerator position sensing and an electronic throttle actuator makes this system very different to the average. For example, the relationship between accelerator pedal position and throttle opening is adjustable - not only can this system control injection and ignition, but also the cylinder charge.
Making ME-Motronic even more of a sea change is the underlying operating logic. Unlike older engine management systems, ME-Motronic determines how much engine torque is required in any given situation, and electronically opens the throttle blade sufficiently to allow the engine to develop that much torque. The accelerator pedal travel becomes just the driver's "torque request" input, to be weighed up against other torque requests that may be generated by the traction control system, speed limiter, engine braking torque control, and others. Additionally, at all times the engine management ECU models the engine's instantaneous torque development, adjusting the throttle opening according to the relationship between the requested and developed torque.
A quick example makes this easier to understand. In some situations, the driver may have only depressed the accelerator pedal to the halfway position - but under the bonnet, the throttle blade can have snapped wide open! But in what type of situation could this possibly be advantageous?
In turbocharged cars, the maximum available torque output of the engine can substantially vary across a quite narrow band of engine speed. For example, the current model Audi S4 twin turbo V6 (pictured as the opener to this story) develops a torque maximum of 300Nm at 1400 rpm and 400Nm at 1850 rpm. So, as can be seen in this Audi graph, across just 450 rpm of engine speed, the peak torque output varies by 33 per cent. This characteristic is caused by the two turbos rapidly coming on boost. To a greater or lesser degree, a similar shaped torque curve is associated with all turbocharged engines.
A driver of a turbo car that is equipped with traditional engine management tends to automatically compensate for this steeply varying torque curve. When wishing to accelerate moderately hard, he or she will initially open the throttle a long way, manually backing it off as turbo boost and torque rises. But the driver of an Audi S4 V6 - equipped with Bosch ME 7.1 - doesn't need to do this. When engine response is relatively poor - ie the turbos are yet to generate appreciable boost - the ME-Motronic system can open the throttle far further than the driver directly requests, and then as revs rise, automatically adjust the throttle angle to retain a linear response. In this way, driveability, emissions and fuel consumption can all be improved.
Inputs and Outputs








As indicated, at first glance the ME-Motronic system looks very similar to other management systems. This Bosch diagram shows the inputs and outputs of a typical ME-Motronic system. In addition to two-way diagnostics and Controller Area Network buses (the CAN buses communicate with other systems such as the automatic transmission ECU), the inputs comprise:
* Vehicle speed;
* Transmission gear;
* Camshaft position;
* Crankshaft speed and position;
* Dual oxygen sensors (located either side of the catalytic converter - 'V' engines have four sensors);
* Knock sensor;
* Coolant temperature;
* Intake air temperature sensor;
* Battery voltage;
* Intake air mass (plus frequently manifold pressure);
* Throttle position
None of these inputs is unique to this system, but the following one is:
* Accelerator pedal position.
With one exception, the outputs are also very similar to other recent management systems:
* Spark plugs;
* Injectors;
* Instrument panel tachometer;
* Fuel pump relay;
* Oxygen sensor heaters;
* Intake manifold runner control (ie control of the position of valves within dual tuned length manifolds, or the length of infinitely variable intake runners);
* Fuel system evaporative control, secondary air injection and exhaust gas recirculation (all emissions control approaches).
The unique addition is the:
* Electronic throttle control actuator
Given that the additional hardware comprises the accelerator pedal position sensor and electronic throttle control actuator, let's have a look at these two components in more detail.


"

*


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## The_RoadWarrior (Nov 21, 2011)

More:


* Accelerator Pedal Position Sensor
Two approaches are currently used in the design of this sensor, but they are electrically identical. The throttle pedal assembly from an Audi S4 is shown here. Movement of the accelerator pedal manipulates two rotary potentiometers; unlike some electronic throttle engines, no back-up Bowden cable exists to connect accelerator pedal movement to the throttle blade. Two potentiometers are fitted to the sensor to allow redundancy - if one should fail, the other still lets the system operate








As can be seen here, the outputs of the potentiometers are identical but for an offset. Cars equipped with automatic transmissions do not have an additional kickdown switch in the assembly; instead a 'mechanical pressure point' is used to give the feel of a kickdown switch.








In the event that the accelerator position sensor fails, the lack of any mechanical connection between the accelerator and the throttle blade requires that sophisticated 'limp home' techniques are in place. The Audi S4 uses two techniques:
Emergency running program #1
This occurs when a single accelerator position potentiometer fails.
* Throttle position is limited to a defined value;
* In the case of implausible signals from the two potentiometers, the lower value of the two is used;
* The brake light signal is used to indicate when idling speed should be enacted;
* The fault lamp is illuminated.
Emergency running program #2
This occurs when both accelerator position potentiometers fail.
* The engine runs only at idle speed;
* The fault lamp is illuminated.
Interestingly, if in the Audi the accelerator and brake pedals are depressed together, the throttle valve is automatically closed to a defined small opening. However, if the brake is pressed and depressing of the accelerator then follows this, the torque request is enabled. I assume that the latter provision is solely for those who like to left-foot brake, with applications of power used to balance the car!





Electronic Throttle Control Actuator








The Audi S4 electronic throttle valve consists of a DC motor, reduction gear drive and dual feedback angle sensors. It is again for reasons of redundancy that two potentiometers are used for angle feedback. However, unlike the accelerator position sensor, these sensors have opposite resistance characteristics to one another, as shown below.








While continuous sensing of throttle blade position does occur, the ECU recognises four key functional positions of the throttle blade:
* Lower mechanical limit stop - the valve is totally shut.
* Lower electrical limit stop - the lower limit used in normal operation. This position does not totally close the valve, thus preventing contact wear of the housing and throttle blade.
* Emergency running position - the position of the valve when it is not energised. This allows sufficient airflow for an idle speed a little higher than standard.
* Upper electrical limit stop - the blade is fully open.
The control system has a self-learning function, whereby the state of the mechanicals within the electronic throttle (eg spring tensions) is determined by the evaluation of the throttle valve's reaction speed.
As with the Accelerator Pedal Position Sensor, sophisticated limp-home techniques are available should the Electronic Throttle Control Actuator develop problems. These include:
Emergency running program #1
This occurs when an angle sensor within the throttle body fails or an implausible signal is received. Required is an intact throttle angle sensor and plausible mass airflow measurement.
* Torque increasing requests from other systems are ignored (eg from the Engine Braking Control);
* The fault lamp is illuminated.
Emergency running program #2
This occurs if the throttle valve drive fails or malfunctions; it requires that both throttle valve potentiometers recognize the Emergency Running Position of the throttle blade.
* The throttle valve drive is switched off so that the valve defaults to the small emergency running opening;
* As far as possible, ignition angle control and turbo boost control(!) are used to execute driver torque demands.
* The fault lamp is illuminated.
Emergency running program #3
This occurs if the throttle valve position is unknown and/or if the throttle valve is not definitely known to be in the Emergency Running Position.
* The throttle valve drive is switched off so that the valve (hopefully!) defaults to the small emergency running opening;
* The engine speed is limited to approximately 1200 rpm by fuel injection control;
* The fault lamp is illuminated.
An Audi schematic diagram showing the operation of the electronic throttle system is shown here.








As you can see, Bosch engineers have been very careful to ensure that a failure of the electronic throttle system will not cause the car to suddenly have full power - or a stalled engine.



*


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## The_RoadWarrior (Nov 21, 2011)

Finally:


* As discussed last week, the Bosch ME-Motronic engine management system is a radical departure from previous electronic engine management. The relationship between the accelerator pedal position and the opening angle of the throttle valve is no longer fixed; instead the Electronic Control Unit (ECU) determines how much torque the engine is required to produce and then opens the throttle valve to the appropriate angle. The chosen throttle opening is based on complex software that models the engine's instantaneous torque output and compares this with the required torque output, as requested not only by the driver but also by in-car systems.
The Audi twin turbo V6 (pictured above) is an example of an engine equipped with ME-Motronic management.
Torque Control Logic








The ME-Motronic system prioritises and coordinates torque demands in order that it can implement an overall torque control strategy. As this Audi diagram shows, torque requests are categorised as 'Internal' or 'External'. External torque requests include those made by the driver, cruise control system and driving dynamics systems like Automatic Stability Control. Internal torque requests are those made by the internal programming of the ECU - factors such as engine governing and idle speed control. The total requested torque is then modified by strategies such as those which take into account catalytic converter temperature or driving smoothness.
In older engine management systems, the driver - via the mechanical alteration of the throttle blade angle - exercised direct control over the mass of cylinder charge, while the management system was limited to torque reduction strategies (eg by fuel cuts) or minor torque increases through manipulation of the mass of air bypassing the throttle. However, this approach does not cope very well with competing and contrary torque demands that may well occur simultaneously. This Audi diagram shows some of the required torque variations found in current cars, excluding those requested by the driver.








The ME-Motronic system internally models the net torque development of the engine. This model takes into account losses through internal friction, pumping losses, and parasitic loads such as that of the power steering and water pumps. Internal mapping within the ECU allows optimal specifications for charge density, injection duration and ignition timing for any desired net torque value, taking into account the often conflicting requirements of best fuel economy and emissions. These requirements dictate that the system must perform well in transients (ie sudden changes in torque), as well as when being subjected to steady-state loads. To allow good performance in both constant and transient load conditions, two different control approaches are taken.
The first control strategy is termed by Bosch the Charge Path. 'Charge' in this context refers to the mass density of air trapped in the cylinder. At a given air/fuel ratio and ignition advance, the mass of this air is directly proportional to the force generated during the combustion process. The Charge Path, controlled by the opening angle of the throttle blade (and boost pressure in a forced induction car), is used to control engine torque output in static operations. The ability of this control system to change quickly is limited by the regulating speed of the throttle actuator and the time constant of the intake manifold, which can be as high as several hundred milliseconds at low engine speeds.
The other technique used to control torque output is termed, somewhat oddly, the Crankshaft Synchronous Path. This refers to torque variations able to be rapidly created by changes in ignition timing and injection operation, with the latter used to effect the air/fuel ratio. Examples of when this approach is employed include torque reduction during automatic transmission gear changes and when Vehicle Stability Systems are operating.

Getting confused? This Bosch diagram puts it all together.








On the far left is the driver, who (at least on the diagram!) is still given pride of place. The driver request for torque is prioritised and processed in terms of driveability functions. These include filtering and slope-limiting, dashpot (to ensure that torque changes do not occur too quickly) and anti-jerking. These functions can be calibrated to suit a wide range of applications - for example a high level of anti-jerk to suit a luxury car, or very quick throttle response to suit a sports car.
In addition to the driver's torque request, other torque variations (for example, an increase in torque to operate the air conditioner compressor, or a reduction in torque required by the load change damping system) are processed, with the final request then fed into the 'Torque to charge density conversion' box. When a torque request is made, the ECU must calculate how much fresh air mass is required to be inhaled by the engine to meet this demand. The actual mass of air that is needed will be dependent on ignition timing (eg if the engine is running relatively retarded ignition to decrease oxides of nitrogen emissions, more air will be needed because efficiency will be lower), internal engine friction, the instantaneous air/fuel ratio and other factors.
Once a mass airflow that will meet the requirements is quantified, a throttle valve opening angle is calculated. However, in all engines, the required angle will be dependent on the manifold pressure, and in forced aspirated engines, manifold pressure will be quite critical to the mass of air actually inhaled. Thus, in these engines the turbocharger boost pressure and throttle valve opening are both specified such that the appropriate charge density required for the prescribed torque output is reached.
Calculating Cylinder Charge
As can be seen from the above, the accurate calculation of cylinder charge is vital if the torque modelling strategy is to be effective, and if appropriate amounts of fuel are to be accurately added to this air. Traditionally, a mass airflow meter positioned between the airfilter box and the throttle body has been used to measure intake airflow. However, the mechanical design of engines is now taking advantage of techniques that maximise cylinder charge in a way in which an averaged mass airflow measurement may not be able to accurately sense.
In the ME-Motronic system the available sensors are used as inputs to a charge air model, rather than being evaluated directly. The requirements for such a charge air model are:
* Accurate mass charge air determination in engines using resonant tuned and/or variable length intake manifolds, and engines using variable valve timing;
* Accurate response to Exhaust Gas Recirculation conditions;
* Calculation of required throttle valve aperture (and required turbo boost in forced induction engines).
While the engine is subjected to a constant load, mass airflow measurement is relatively accurate: ie if Xkg of air per second is passing through the airflow meter, it can be assumed that all of it is ending up in the cylinders! However, during transients, the situation is much more complex. For example, if the throttle blade is abruptly opened, the intake plenum chamber will rapidly fill with air. For an instant this will give an inaccurately high reading from the airflow meter - the meter will indicate a higher cylinder charge than has actually had time to occur. It is only when intake manifold pressure has risen that the flow will commence into the cylinders.
As a result of this characteristic, the ME-Motronic system generally uses both manifold absolute pressure (MAP) and hot wire airflow meter (HFM) inputs. (In some cases the MAP sensor is not fitted; further software modelling duplicates its function.) The HFM is a further development of the design used by Bosch and other management systems for about 15 years. Its improvements result in better accuracy; for example, it is capable of differentiating reverse flow pulses from airflow passing into the engine. 

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## 1fast2liter (Apr 4, 2005)

So does it work?


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## H3NTA1 (Nov 25, 2010)

1fast2liter said:


> So does it work?


Yes, but for what manofmanygts says its to responsive for others. my buddy got one on his car and doesn't even use that race mode. Its like driving a crotch rocket. He said it was cool at first but then hated it. Shifting sucks he says. Ill ask him if he cud do a video for us...


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## Marcus_Aurelius (Mar 1, 2012)

1fast2liter said:


> So does it work?


Simple answer is yes!
If you cared to read Roadwarrior's post you would understand how and why it works too.


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## Marcus_Aurelius (Mar 1, 2012)

H3NTA1 said:


> Yes, but for what manofmanygts says its to responsive for others. my buddy got one on his car and doesn't even use that race mode. Its like driving a crotch rocket. He said it was cool at first but then hated it. Shifting sucks he says. Ill ask him if he cud do a video for us...


That is suppose to be the whole point isn't it? Enhance the DBW responsiveness to various degree. 

I don't see why it sucks if someone is trying to drive to the convenience store on a *Race* setting. Race means "track-like" situations where you can actually make use of the fast transition from throttle pedal (calculated request) to actual throttle body plate angle.


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## Atomic Ed (Mar 19, 2009)

I have one and for daily driving...meh. I would not recommend it for the money. Full throttle is reached at about 3/4 of the pedal movement, making it harder to feather the throttle. If I was road racing and wanted that extra 1/4 sec going to full throttle, then, ya, it's maybe worth it. 

Go read this PDF file:

http://bipesauto.com/sprintbooster/

Like the article says:

"The Sprint Booster is a simple amplifier that multiplies the accelerator pedal
sensor signal, making the accelerator pedal more sensitive. It does not eliminate
any significant delay in throttle response, nor does it greatly improve acceleration
figures. It does not change the adaptive throttle control programming of
electronic throttle control vehicles. It does change pedal “feel”. This change in
feel is interpreted by some as improved throttle response, acceleration, and a
change in adaptive throttle control programming. Considering what it actually
does, it is expensive."


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