# TT-RS Flapper mod How-To



## bigstu (Mar 6, 2008)

Hello everyone,

I flapper modded my new TT-RS last week. I love the sound of the exhaust in sport mode, but don't like to keep sport mode on all the time because the magride is really firm in sport. I have put over 1000 miles of driving since flapper modding and have received no CEL's, just a better exhaust note that never droans or is too loud. I have the sport exhaust option, and it sounds really really good open all the time.

The process is easy: get under your car (jack not required) behind the drivers side exhaust tip. Stick your head under there and you will see the flapper module for the exhaust. All you need to do is zip tie the vacuum line closed. There is even a metal clip there to hold the vacuum line, that I zip tied the line to. Whole process took all of 5 min, only need 1 zip tie, and is completely reverse-able at anytime. You can also disconnect the vacuum line and plug the holes, but the zip tie method is easiest, cuz everyone has zipties, but finding the perfect plastic plugs for those holes isn't easy.

Here is a pic, everyone needs to do this right now - sounds so much better!!!! 

TT-RS Flapper Mod:









One of the car for good measure:


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## unclubbedvdub (Jul 19, 2002)

Bump for a still spotless undercarrage


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## JohnLZ7W (Nov 23, 2003)

Think something like this might work? Should be possible to get small enough diameter piping at an aquarium supply place


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## joshsmith (Apr 17, 2011)

That's mad! Im gonna go do mine now. But firstly, how do I ensure the valve is open to begin with??


Sent from my iPhone using Tapatalk


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## R5T (Apr 7, 2010)

bigstu said:


> One of the car for good measure:


Great stance with the H&R's.


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## tdi-bart (Feb 10, 2011)

the valve is open by default, the hose only closes it i think

but isnt the car louder now under 3k rpm too, as not only does it open in sport mode, but also gets louder above 3k rpm due to the ecu controlling it...

i was thinking about doing it but i was thinking it might sound crappy at low rpms not as classy


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## DrDomm (Feb 16, 2003)

R5T said:


> Great stance with the H&R's.


Stu, you have H&R sport springs? Any thoughts? Problems?


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## joshsmith (Apr 17, 2011)

tdi-bart said:


> the valve is open by default, the hose only closes it i think
> 
> but isnt the car louder now under 3k rpm too, as not only does it open in sport mode, but also gets louder above 3k rpm due to the ecu controlling it...
> 
> i was thinking about doing it but i was thinking it might sound crappy at low rpms not as classy


I see.. On a cold start it's loud, but I press S straight away, once the revs drop I hear the flap open.. So I don't want to tie the thing shut! Haha. 


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## Black BeauTTy (Jun 11, 2011)

DrDomm said:


> Stu, you have H&R sport springs? Any thoughts? Problems?


I have the same questions. I may have the AWE boys do the springs while we're fabricating the ultimate exhaust. :laugh:


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## Black BeauTTy (Jun 11, 2011)

JohnLZ7W said:


> Think something like this might work? Should be possible to get small enough diameter piping at an aquarium supply place


That's pretty cool but the solution I'm working on with AWE will make that unneccessary! Think in-cabin selection option.


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## JohnLZ7W (Nov 23, 2003)

Black BeauTTy said:


> That's pretty cool but the solution I'm working on with AWE will make that unneccessary! Think in-cabin selection option.


I figure for day-to-day commuting and just running around I'll want full volume but for road trips and longer drives it'd be nice to calm it down a bit. Throw suitcases in trunk, flip the valve open and hit the road


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## joshsmith (Apr 17, 2011)

Ok so I have the cable tie here with me and will be putting it on shortly.

Are you sure that the default position for the flap is open?


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## Black BeauTTy (Jun 11, 2011)

Yep, default is open...no vacuum, no closure.


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## joshsmith (Apr 17, 2011)

Black BeauTTy said:


> Yep, default is open...no vacuum, no closure.


Shweet!! Hope this makes it noticably louder at that lower RPM and doesn't bring up any faults!! 

I'll get it done when I get home from work and let you all know how I've gone!


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## DrDomm (Feb 16, 2003)

Black BeauTTy said:


> I have the same questions. I may have the AWE boys do the springs while we're fabricating the ultimate exhaust. :laugh:


I thought the H&R's gave more fender gap up front on the TTS's. Same for the RS's? I'm considering the Eibach's, as well. For spring...no pun intended.


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## joshsmith (Apr 17, 2011)

Ok was DEFINITELY worth while!!! Sounds awesome! Just seems to make 1000-4000rpm louder and meatier, the way it should be . It basically means, (for those of you who know) the noise you get in 4th gear at around 2000-2200rpm under a bit of load - you now get that in all gears. Sounds good. And the cold start this morning was EPICLY loud!! Really enjoying it, such a simple thing to do! Can't wait to find the "right" exhaust!! 

Does anyone know; the TTRS sport exhaust, is that louder than it is currently with the flap permanently open?? I want to see if I can import it here as sometimes the car sounds like it is muffled and is just begging to scream.


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## Black BeauTTy (Jun 11, 2011)

joshsmith said:


> Does anyone know; the TTRS sport exhaust, is that louder than it is currently with the flap permanently open?? I want to see if I can import it here as sometimes the car sounds like it is muffled and is just begging to scream.


The problem is the primary cat. My car is with AWE right now and the plan is to address this limitation! Oh man, I can't wait to hear this thing unleashed!


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## DrDomm (Feb 16, 2003)

Black BeauTTy said:


> The problem is the primary cat. My car is with AWE right now and the plan is to address this limitation! Oh man, I can't wait to hear this thing unleashed!


Will they have a "high flow" primary cat? I mean, there are laws, right? Ironically, I just got an email that my secondary cat bypass pipes just shipped from the UK. Cool.


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## Black BeauTTy (Jun 11, 2011)

DrDomm said:


> Will they have a "high flow" primary cat? I mean, there are laws, right? Ironically, I just got an email that my secondary cat bypass pipes just shipped from the UK. Cool.


Yes and yes. Work is underway on a new DP design with high flow cat.


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## JohnLZ7W (Nov 23, 2003)

DrDomm said:


> Will they have a "high flow" primary cat? I mean, there are laws, right? Ironically, I just got an email that my secondary cat bypass pipes just shipped from the UK. Cool.


I'm glad you posted this... I had received my ship notice too but had deleted it because it looked like spam. What's gonna get here first, the car or the pipes?


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## mtbscoTT (Jan 14, 2003)

Okay, I did this mod yesterday....and I'm not thoroughly convinced that the exhaust flap is staying open all the time. I only drove a short bit last night after doing it, with the windows down, and at lower engine speeds (where I expected to hear the difference) it just didn't seem that much louder. Weird, how when I pushed the button to engage Sport mode, I could hear the difference, but not being able to switch back and forth makes it more subjective.
Drove to work this morning with windows up (chilly by Texas standards), and still unsure. The clincher to me was I touched the exhaust finishers after I parked and the driver's side was still cool to the touch while the passenger side was warm. I'm wondering if somehow my ty-wrap isn't quite shutting off all vacuum to the flap?


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## DubaiJohn (Aug 29, 2006)

Just to chime in on this one. When I had my secondary cat bypass pipes fitted I had the vacuum pipe removed and both the pipe and the connection on the flapper blocked off. I can confirm that this makes the exhaust flap open all the time. 

Also on a cold start with Sports Exhaust + bypass pipes fitted it sounds as though a minor war is breaking out in my garage. 

Can't wait to get the Pipercross filter fitted. Then onto Abt Intercooler and remap!


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## - Jeremy - (Feb 23, 2006)

DubaiJohn said:


> Also on a cold start with Sports Exhaust + bypass pipes fitted it sounds as though a minor war is breaking out in my garage.


Hell-****ing-YES!

I'm doing the bypass pipes. But I'm also curious... Has anyone bypassed both the secondary cats AND the small resonators before the muffler? It would be akin to the Milltek Race setup. This is what I want to try, but if someone tells me it sucks, then I won't bother. I've never seen anyone do it. All I know is that I want the Milltek race setup, but without the required ECU remap and the requisit $3000 payment 

- Jeremy -


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## JohnLZ7W (Nov 23, 2003)

- Jeremy - said:


> Hell-****ing-YES!
> 
> I'm doing the bypass pipes. But I'm also curious... Has anyone bypassed both the secondary cats AND the small resonators before the muffler? It would be akin to the Milltek Race setup. This is what I want to try, but if someone tells me it sucks, then I won't bother. I've never seen anyone do it. All I know is that I want the Milltek race setup, but without the required ECU remap and the requisit $3000 payment
> 
> - Jeremy -


Yes I believe 996Cab (who posts here on occasion) has also removed the rear resonators. It's on my list of things to try unless someone comes out with a really good catback setup.


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## bigstu (Mar 6, 2008)

bumping this thread for new TT-RS owners.....flapper mode you're car and let that exhaust sing!!


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## DaveTT (Mar 22, 2000)

Just did this yesterday, slid under the car, pulled the vacuum line off and plugged it with a screw, 10 mins. Now it sounds great all the time, secondary cat bypass next


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## joshsmith (Apr 17, 2011)

I did this to my car; however I asked my mates who work at Audi service and as mechanics etc.. They reckon that by doing this you lose a bit of back pressure.. I'm not sure however their argument was that it was put there for a reason and opens when there is a certain amount back pressure through the exhaust it opens to release. (noise too).. I took mine off after a few weeks just to be on the safe side.. I loved the noise with it but am slightly concerned about losing performance for the sake of some slight extra noise up to 3500rpm


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## Marty (Jul 14, 2000)

joshsmith said:


> I did this to my car; however I asked my mates who work at Audi service and as mechanics etc.. They reckon that by doing this you lose a bit of back pressure.. I'm not sure however their argument was that it was put there for a reason and opens when there is a certain amount back pressure through the exhaust it opens to release. (noise too).. I took mine off after a few weeks just to be on the safe side.. I loved the noise with it but am slightly concerned about losing performance for the sake of some slight extra noise up to 3500rpm


So your mates' argument is that the car makes less power in "Sport" mode?


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## JohnLZ7W (Nov 23, 2003)

joshsmith said:


> I did this to my car; however I asked my mates who work at Audi service and as mechanics etc.. They reckon that by doing this you lose a bit of back pressure.. I'm not sure however their argument was that it was put there for a reason and opens when there is a certain amount back pressure through the exhaust it opens to release. (noise too).. I took mine off after a few weeks just to be on the safe side.. I loved the noise with it but am slightly concerned about losing performance for the sake of some slight extra noise up to 3500rpm


Find new mechanics.


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## NoPasaran (Feb 29, 2012)

I have OEM Sport exhaust, I had the Pre-Cat removed and had the flap fixed permanently open. 

The noise is nice, very high on cold start-up, not all neighbours are happy at 7am on a weekend morning. :wave:

I've also had the second bypass pipes installed last summer. The response was noticeably better and the noise was also higher, especially loud when I accelerated in 6th gear from 2000rpm in tunnels.  
I put the main cats back on as the car stinks really bad otherwise and I do not want to have any problems with the police either (I've got stopped once for being "too loud", thank God at that point I had the cats back on).

I will be replacing the two small silencers with a straight pipe, this will add about 1.5dB and hopefully also some more "structure" to the exhaust sound.  Everyone who installed these silencer bypass pipes say the sound is very nice, especially when the Pre Cat is removed.


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## NoPasaran (Feb 29, 2012)

JohnLZ7W said:


> Find new mechanics.


+1


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## joshsmith (Apr 17, 2011)

Marty said:


> So your mates' argument is that the car makes less power in "Sport" mode?


No, because when in Sport mode the exhaust flap is NOT always open.. If you listen carefully, when you press it and it opens, once you change into 2nd gear it actually closes until you get back to 3000rpm+ and same in 3rd. I'm not sure of the nuts and bolts of it, I'm just questioning whether it really is good for the car as it runs off a vacuum apparently which ultimately can effect things along the line i.e. backpressure etc.

I'd be interested in feedback; I didn't notice any power increase/decrease to be honest. 

Has anyone noticed any differences in the way that the car drives?


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## Marty (Jul 14, 2000)

joshsmith said:


> No, because when in Sport mode the exhaust flap is NOT always open.. If you listen carefully, when you press it and it opens, once you change into 2nd gear it actually closes until you get back to 3000rpm+ and same in 3rd. I'm not sure of the nuts and bolts of it, I'm just questioning whether it really is good for the car as it runs off a vacuum apparently which ultimately can effect things along the line i.e. backpressure etc.
> 
> I'd be interested in feedback; I didn't notice any power increase/decrease to be honest.
> 
> Has anyone noticed any differences in the way that the car drives?


My car sounds like the flapper automatically opens at low RPM with enough gas while I'm shifting. It's a very distinct sound difference as the valve closes automatically as load decreases.

That would make sense, though, since it's vacuum-actuated. Flooring the car drops the vacuum levels back to atmospheric pressure, so the flap might always open when you floor it. So then Sport mode is only opening the flapper when you're at light load (all the time)?


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## JohnLZ7W (Nov 23, 2003)

joshsmith said:


> No, because when in Sport mode the exhaust flap is NOT always open.. If you listen carefully, when you press it and it opens, once you change into 2nd gear it actually closes until you get back to 3000rpm+ and same in 3rd. I'm not sure of the nuts and bolts of it, I'm just questioning whether it really is good for the car as it runs off a vacuum apparently which ultimately can effect things along the line i.e. backpressure etc.
> 
> I'd be interested in feedback; I didn't notice any power increase/decrease to be honest.
> 
> Has anyone noticed any differences in the way that the car drives?


There's no loss of vacuum though, it's not like people are just disconnecting the hose and leaving it. Do they also think that adding a vacuum tap to run a boost gauge will decrease performance? What do the think about running a freer flowing exhaust on a turbocharged car?


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## fourtunes (Sep 16, 2011)

On a related note, I came across this thread recently in which an alternative to the zip-tie is being discussed. 

In a nutshell, someone took a closer look at the wiring diagrams/etc. and found that the wire between the ECU and the magnetic valve that controls the vacuum pressure to the exhaust flap runs through the trunk (on the left-hand side, below the Bose amplifier). So what a few owners have done is to cut that wire and run the signal through a radio-controlled switch. 

The net effect is the same as with the zip-tie, with two exceptions: 1) you still have control over the flap from the cabin, and 2) the ECU logs fault codes.


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## joshsmith (Apr 17, 2011)

fourtunes said:


> On a related note, I came across this thread recently in which an alternative to the zip-tie is being discussed.
> 
> In a nutshell, someone took a closer look at the wiring diagrams/etc. and found that the wire between the ECU and the magnetic valve that controls the vacuum pressure to the exhaust flap runs through the trunk (on the left-hand side, below the Bose amplifier). So what a few owners have done is to cut that wire and run the signal through a radio-controlled switch.
> 
> The net effect is the same as with the zip-tie, with two exceptions: 1) you still have control over the flap from the cabin, and 2) the ECU logs fault codes.


 So with it Zip Tied it is reading fault codes???


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## mtbscoTT (Jan 14, 2003)

joshsmith said:


> So with it Zip Tied it is reading fault codes???


 No.


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## nnnick (Apr 6, 2009)

Did this last night, wow is cold start loud! Pretty fun mod, not sure if I'll keep it long term as it's kinda loud in certain ranges with my secondary cat bypass, but it's super easy to reverse so going to have fun for a while anyway. Cheers to OP for the write up!


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## quattrohead (Oct 8, 2001)

Just did the cable tie mod, best rumble for the cent in motoring history.


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