# For those with upgraded downpipes for the TTRS



## keitth24 (Dec 5, 2007)

Thinking about getting a bigger downpipe for my tt rs. Did anyone get a CEL? If you guys did, what did you do to get rid of it? did you install a O2 spacer or was it all in the ECU mapping that got rid of the CEL


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## lpriley32 (Jul 28, 2012)

i used an 02 spacer as I am still stock with my ECU. I believe the ecu remap with take care of the CEL without needing a spacer though.


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## DesertTTRS (Dec 17, 2011)

*downpipe*

running Scorpion turbo back with 100cell hi flow cat - GIAC software eliminates any check engine lights - w/o software ran a spacer and still got occasional check engine


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## keitth24 (Dec 5, 2007)

i'm actually running a GIAC software already =). Did they have to specifically update the software for the downpipe or is it already embedded in the software


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## tt-ho (May 26, 2011)

keitth24 said:


> i'm actually running a GIAC software already =). Did they have to specifically update the software for the downpipe or is it already embedded in the software


if its anyting like apr, you'd have to get reflash to stage 2 which should be free upgradel


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## DesertTTRS (Dec 17, 2011)

*GIAC upgraded flash to eliminate error code*


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## keitth24 (Dec 5, 2007)

Would people say that all downpipes have good fitment or is there a specific one that fits better?


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## keitth24 (Dec 5, 2007)

which downpipes do most people have for the TTRS?


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## hightechrdn (Dec 9, 2011)

keitth24 said:


> which downpipes do most people have for the TTRS?


In the US, the APR and 034 Motorsport downpipes appear to the most popular. I would guess that the APR DP is the most used in the US, but that doesn't mean it is "better" per say than the 034 DP. There are a number of European companies producing downpipes for the TTRS, some of which are sold in the US (ex: Milltek). CTS Turbo just recently release a DP for the TT-RS, but I haven't seen any reviews or first hand impressions of their offering yet. 

I have a downpipe from 034 Motorsports. I went with the 034 DP in part because I wanted retain the OEM dual exhaust layout after the DP all the way to the exhaust exits at the the rear of the car. I also have catless mid pipes and a Borla cat back exhaust. The Borla exhaust has an X-pipe section, but does not reduce down to a single pipe at any point like most of the other systems on the market. With no cats or resonators, this combination isn't for people who want a quite car, but has proven to be good for people who want an aggressive exhaust sound.

The APR DP appears to be popular. APR produces good quality parts. The APR DP is a single 3 inch pipe with "sport" cat configuration. APR is making good power with their Stage 3 kits using a singe 3 inch pipe, so it must flow well enough for the 2.5L engine. 

Note that without any cats, you will need O2 spacers or an ECU tune to avoid a CEL with the 034 DP or any other DP for that matter. The alternative is to add "sport" cats ust after the DP to clean up the exhaust. You could then relocate the O2 sensor to be just after the "sport" cats, in one of the mid pipes. This is similar to how APR deals with the O2 sensor, but APR uses a single pipe/sport cat setup. Another approach to deal with cat CEL's is to use O2 spacers, which is a very popular option in the VAG world. They don't always eliminate the CEL's, but they do seem to work most of the time on the TT-RS.

Personally, I recommend the 034 DP. However, the best choice for you is going to vary based on your plans for other modifications, cat back exhaust, etc.


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## Black BeauTTy (Jun 11, 2011)

HJS makes several high quality cats that are capable of flowing well AND passing emissions without the software or spacer shenanigans. The model needed depends on HP and displacement. A tuned TTRS is on the edge of the power spec for a single sport cat that is around $400 so it makes sense to run 2 of them in a dual pipe config. Their universal cat can handle massive power and can be run by itself in a single pipe config but costs around $1,200.


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## canuckttrs (Feb 5, 2012)

these guys are in vancouver and sell a dp for the ttrs.

http://www.ctsturbo.com/cart/products/CTS_Turbo_TTRS_High_Flow_Downpipe-4470-0.html

less expensive than the rest and better cost for shipping when you include duty from down below.


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## keitth24 (Dec 5, 2007)

Awesome I saw them post a few weeks ago about the new downpipe. I don't think anyone has these installed yet right? I am a little nervous being the first and then having fitment issues


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## keitth24 (Dec 5, 2007)

Anyone feel nice gains from the down pipe? asides from the wonderful noise?


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## keitth24 (Dec 5, 2007)

The o2 spacer goes at the second sensor right?? Dumb question but just want confirmation


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## hightechrdn (Dec 9, 2011)

keitth24 said:


> The o2 spacer goes at the second sensor right?? Dumb question but just want confirmation


The TT-RS only has one O2 sensor, which is mounted just after the primary cat, very near the turbo. It does not use a second (set) of O2 sensors after the secondary cats.

A high quality aftermarket cat with fairly high cell count can likely pass emissions and not throw a CEL on a TT-RS, since the TT-RS doesn't use the more stringent O2 checks (including post cat O2 sensors) like the CA specific 2.0 TSI (and other) engines do. However, if you read up on the ECU strategies used by the OEM's to identify cat/engine emissions problems, they are much more than a simple check of the O2 reading against a lookup table. If a cat is borderline but passing when new, it may not stay 100% CEL free as it ages. A O2 spacer could be required after some time/miles to avoid CEL's. There are many reports of O2 spacers working on TT-RS models with success, so this wouldn't be the end of the world, but thought this might be useful information to share.


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## keitth24 (Dec 5, 2007)

It appears all the upgraded down pipes removes the primary cat right?


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## hightechrdn (Dec 9, 2011)

keitth24 said:


> It appears all the upgraded down pipes removes the primary cat right?


The 034 DP does remove the primary cat. It doesn't include the mid pipe section, so you will end up with just the OEM secondary cats, secondary cat delete pipes (034 sells them separate from the DP), or some custom setup.

APR's DP removes the OEM primary and secondary cats, as their DP includes the mid pipe section. APR includes 1 cat, located away from the turbo/engine closer to the OEM secondary cat location (may actually be in the DP section technically, but is under the car instead of up by the turbo).

Hope this helps.


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## CarbonRS (Jul 15, 2013)

I installed an APR downpipe without a tune recently with a Griffin Motorwerke O2 Sensor Spacer and it is throwing a CEL frequently, especially when coasting off the highway. Which spacers have been more successful? I'm wondering if i could just modify the one I have if it needs more or less flow. It is usually code P2271, but I did see P2096 once.

Thanks!


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## lpriley32 (Jul 28, 2012)

http://store.42draftdesigns.com/O2-Sensor-Spacer_p_306.html

I am using this with my APR downpipe and stock ecu. No CELs as long as I have had it and that has been a good 20k miles I would think give or a take some...but it has been a lot.


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## CarbonRS (Jul 15, 2013)

Thanks! That was actually the one we were going to use, now I'm kicking myself for asking for the Griffin one. It looks like the difference is the 42DD has more flow. I'll try modifying it to match.


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## Not4show (Jun 11, 2004)

I run a APR DP, no CEL's about 2k miles since I put it on.


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## crew219 (Oct 18, 2000)

Not4show said:


> I run a APR DP, no CEL's about 2k miles since I put it on.


If you upgraded to stage 2 programming, you wouldn't have a CEL because it is coded out via the software.


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## Not4show (Jun 11, 2004)

crew219 said:


> If you upgraded to stage 2 programming, you wouldn't have a CEL because it is coded out via the software.



Stock program. Apr moves 2nd O2 downstream 

Also have APR FMIC waiting for install. Trying to recover from broken back once I'm good to work do stuff again, Ill get the FMIC installed and send out the ECU for stage 2.


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## CarbonRS (Jul 15, 2013)

I sorted out my issue, just in case anyone else is coming here looking for info. When we looked at the sensor output, it looked like it was stuck, but it was actually just reading very high, probably stuck at the high end of it's range. We used an o2 defouler to bring it back in range. You could weld an o2 spacer shut and drill a small hole in it, making the hole larger until you get the reading your want, or use something like this: http://vibrantperformance.com/catalog/product_info.php?cPath=1022_1069&products_id=1605
http://vibrantperformance.com/catalog/product_info.php?cPath=1022_1069&products_id=2009

I don't know the brand of o2 defouler we ended up using, but the restrictor looks about the same as the smallest one in the vibrant kit.

Found this elsewhere on VWV for which blocks to look at while testing and making sure it is just the secondary O2 that is acting up:



> In order to test your MAF, O2 sensors and catalytic converter, check out the following blocks in the "Engine" control module with your VAG-COM. Blocks 002, 030, 032 and 033 are done in "Measuring Blocks" while blocks 036, 034 and 046 are done in "Basic Settings". Let me know if you have any questions about how to run the tests. (NOTE: The following tests are MKIV VR6 specific. If you have a 1.8T or 2.0 engine, the procedure from running the automated tests is slightly different. For a 1.8T engine, see this THREAD for instructions on how to initiate the tests. I'm not positive about the initiation procedure with a 2.0 engine, but from what I've found, with an AEG engine you manually raise the engine speed to between 1800 and 2200 RPMs, and with the AVH and AZG engines, you derpress the accelerator to the WOT (wide open throttle) position to raise the engine speed to ~2000 RPMs.
> 
> Block 002 - Load Registration
> 
> ...


Block 036 is the one to watch.

Also, if you ever get the mag ride light on your dash after jacking it up. In my case the front wheels off the ground on axle stands, the code will keep coming back until your pull the battery.


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