# Catless downpipe/straight pipe with APR Stage 1



## Checkers10160 (Jun 4, 2013)

So I just picked up a Relentless Performance Downpipe and Straight pipe, which I want to put onto my 01 TT 225Q. I also plan on getting a Stage 1 tune done in a few days. When the straight pipe is installed, will I still need a spacer for the o2 sensor, or can I just clear the code with the APR software? Will the car throwing a code cause any performance issues, like compensating for the increased air ration?

And on another note, if anyone is in the NY/CT area with experience replacing downpipes and can help me in exchange for food and beer, please let me know. I'll pay for gas, I just don't feel comfortable taking this on myself

EDIT: Also, do you guys' downpipes say "Relentless"? My straight pipe does, and the welds look identical, but there's no branding on the DP itself


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## toy4two2 (Feb 6, 2012)

Checkers10160 said:


> So I just picked up a Relentless Performance Downpipe and Straight pipe, which I want to put onto my 01 TT 225Q. I also plan on getting a Stage 1 tune done in a few days. When the straight pipe is installed, will I still need a spacer for the o2 sensor, or can I just clear the code with the APR software? Will the car throwing a code cause any performance issues, like compensating for the increased air ration?
> 
> And on another note, if anyone is in the NY/CT area with experience replacing downpipes and can help me in exchange for food and beer, please let me know
> 
> EDIT: Also, do you guys' downpipes say "Relentless"? My straight pipe does, and the welds look identical, but there's no branding on the DP itself


you will need to buy a spacer. 42DD makes a good looking one. I have APR stage 1 and don't know anyway you can code it out yourself, you need to talk to APR about getting that mod done. Gonzo Tuning also offers this service. That O2 sensor does nothing so it won't effect performance, you just won't pass smog visual for a CEL


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## Checkers10160 (Jun 4, 2013)

toy4two2 said:


> you will need to buy a spacer. 42DD makes a good looking one. I have APR stage 1 and don't know anyway you can code it out yourself, you need to talk to APR about getting that mod done. Gonzo Tuning also offers this service. That O2 sensor does nothing so it won't effect performance, you just won't pass smog visual for a CEL


Ok, thank you. APR is having their big sale (Full package for $500) including the fault code erase, which I took to mean "Clearing CELs" but I may be wrong. I was just worried the engine would see a bad ratio in the exhaust and run lean to compensate for what the cats would've filtered out. So basically if I run it with a CEL on for a week or two while I wait for the spacer to be delivered, I should be fine?

Also, does the downpipe allow me to go stage 2 or will I need a full exhaust/intake?


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## toy4two2 (Feb 6, 2012)

I believe the APR CEL mod just lets you clear codes using the cruise control stalk, not the o2 sensor delete.

If I were you I wouldn't get the APR tune. Its a good tune, I currently have a APR 91 octane program and stock on my 2002, however, Gonzo Stage one is a better value and you can tick off custom items you want like secondary o2 sensor delete, SAI delete, and IMMO off (I recommend all of those) and others say the APR is the most conservative tune compared to the others.

Running without the 2nd o2 sensor will do NOTHING bad to your car, all the air/fuel decisions handled by the ECU are done off the 1st o2 sensor. All the 2nd really does is tells you if your catalytic converter is working correctly or not.

I don't know what parts you need for each stage of tune, but Gonzo lists them on his page, I don't know how this translates to APR's Stage 1/2/3 (didnt have anythign but 1 when I bought my APR tune).

https://www.gonzotuning.com/tuning/audi/tt-mk1/


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## Checkers10160 (Jun 4, 2013)

toy4two2 said:


> I believe the APR CEL mod just lets you clear codes using the cruise control stalk, not the o2 sensor delete.
> 
> If I were you I wouldn't get the APR tune. Its a good tune, I currently have a APR 91 octane program and stock on my 2002, however, Gonzo Stage one is a better value and you can tick off custom items you want like secondary o2 sensor delete, SAI delete, and IMMO off (I recommend all of those) and others say the APR is the most conservative tune compared to the others.
> 
> ...


Alright, thank you very much. I'm happy to hear it shouldn't harm it if I can't do them together. And I looked into Gonzo a little bit, but I kind of like that APR is conservative, and they have such a huge backing, plus a great reputation. And the Gonzo dealers are nowhere near me, so I'd be a little worried about getting a tune and not being able to go to a brick and mortar shop if something went wrong. I have terrible luck with cars, and it makes me feel better knowing there's an actual place I can take my car if a problem arises.

Plus I saw that if I go with Gonzo later on down the line, they give you $100 off if you switch from a competitor


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