ok...so i have a '03 A4 1.8Tq....the question is what are the pro's and con's to taking out the CAT. and putting in a downpipe/test pipe in place of it, are there any back pressure issues, or anything i would have to worry about?? for now i am running a stock exhaust system, but i think my CAT. is starting to get clogged up, i live in FL where there are no emmission tests (is that correct spelling??) so that doesn't matter to me... let me know.

TIA,

Joe

 

Get a testpipe, you won't be disappointed!
Advantages: More power, turbo spools faster, cheaper then replacing with new cat
Disadvantages: CEL may come on (I use the non-fouler mod and I dont get a CEL), some people notice a smell, but I have no problems
Also, the exhaust will be somewhat louder (could be a plus or minus depending on preference)

 

Doubt your cat is getting clogged. I'm at 175K miles with my cat.

 

Disadvantage - Wont pass inspections in some states.

 

I believe with certain chips like REVO it prevents the CEL to come on. in a few weeks im going to get an EVO TP..custom downpipe..380cc injectors and REVO put in..and i have emissions in my state... also many states dont do the smeller test or visuals really anymore..they just plug into the ecu and read if there are any codes..

 

ok..so yea (JOVIAN)...like i said...i live if florida so i dont have to deal with emmissions tests!! if you can read!! And also what can i get so i dont have a problem with the CEL light because of the after CAT. O2 sensor??

TIA,

Joe

 

All you need to do is put 2 spark plug non-foulers in before the post-cat o2 sensor and it should prevent the cel from coming on. The non-foulers only cost a few dollars at autozone or something. I've been doing this for several months now with no CEL.