I got a 3" exhaust, so decided to start looking for a tp. I remember there were some cheap ones on ebay but now I can only see those 2.5" with a heatshield that are $170 and the greddy 3" tps that cost like $200... my questions are:

1. Can I have a code that will make me fail the emissions even if I dont have a cel? (my state only scans the ecu, no visual or smog).
2. Would it be better to get the 3" or will it not make a big difference? I will probably be staying with my chipped ko3, maybe a k04 j31 file.
3. Do I need two non-foulers or only one for the front sensor, and where can I find those 90* no foulers?
4. Since its still not the same as a cat, will my car run a little worse due to the wrong sensor positioning?

 

1. If you do the non-fouler mod it tricks the ecu into thinking there IS still a cat, so it won't give a code that there isn't a cat. You will even pass a smog (unless you're in CA) just not a visual.
2. the exit of your turbo is 2.75 inches, so you will need to get a 3" (see picture)
3. DO NOT non-fouler the front o2 sensor (the closest to the turbo) that one controls you air:fuel ratio. Non-fouler goes on the back one. I got my non foulers at auto zone.
4. Your exhaust will be less restrictive and run better without a cat.

Here's the TP I got and love it.
http://www.atpturbo.com/Merchant2/me...Code=AUDIVW-DP

 

Wow, thanks alot man, but are you sure the exit is 2.75? the stock exhaust is 2.25 so that would mean the cat has a larger input than output? Why would they have 2.5" test pipes then?
Also, did that tp come with gaskets and bolts? and how much did shipping cost?

EDIT: The pic didn't show up before. I am very surpirsed, why are they selling 2.5" test pipes if the exit is 2.75... unless the test pipe has a larger inlet... What I like about the ebay tp is that the heatshield makes it look like a cat and that it comes with all bolts and both gaskets.
Did you use 2 non-foulers?

 

I'm not sure why they make a 2.5". I know it does come with the bolts, I can't remember if it comes with the gaskets. If not you can get them at Napa or ECStuning. As for the non-foulers you only need to do it to the back O2 sensor. That means that yes you need 2 of them, you drill out the first one so the sensor fits mostly through it, then it goes into a regular non-fouler then into the cat. You will probably get a cel off and on for a couple of months but then it stops.