I am building an exhaust system and was wondering where can i find the best test pipe because i want to relocate the cat...also what kid of muffler sounds good. last think i was planning on using 2.5 inch or 3 what do you guys think>?

Any input would we awesome

2001 a4 1.8t sport quattro

 

Ecode testpipe is great IMO thats what I ran..... as for pipe it depends on your mods and future mods 2.5 is good for k03/k04 but if your planing on going BT you should go with 3' I love borla mufflers so Id say go with them but magnaflow and a few other brands make some sick mufflers too