Have a 2001 Audi a4 1.8t. I have a borla cat back exhaust and I'm looking for a little more sound out of it. I was told to do a 3" down pipe but then some people are telling me to do a 3" test pipe. So my questions are:

What's the difference between a test pipe and down pipe?

I was looking at this:

http://www.ecstuning.com/Audi-B5_A4-...nce/ES1844140/

Will this make it louder? Also seen ill give it a little more power, rpm out of the Turbo so that a a plus too as well.

Thanks

 

Test pipe replaces the cat
Down pipe comes after the cat/Test pipe

If you have a catback exhaust it means you changed the exhaust from the cat untill the muffler, including the downpipe.