Custom Exhaust??
 

I really want to get a custom 2.5 inch or 3 inch cat-back or even turbo back on my 1997 a4 1.8t. i guess im just asking if anyone has thoughts about them such as sound difference from stock to 2.5" or stock to 3". I buddy of mine has a pipe bender so that takes out most of the work but i am still fighting with what size and to do 2.5" or 3". Any comments would be nice and I'm new my car due to me only being 17. I want to have a new sounding exhaust and not all riced and civic sounding. Thanks for the help.

Magnaflow 14816 muffler on a custom-bent 2.5" system is more than enough. Back in my 300ZX days, SpecialtyZ in CA found that a 2.5" exhaust system was able to handle almost 900hp worth of airflow from the VG30DETT engine. 2.5" is plenty for your car, even with a mild turbo upgrade. Search YouTube for "Audi exhaust" and listen to the different tones the mufflers make. The Magnaflow is around $155 or so I believe, and you just have to cut the OEM muffler off and weld in the new one.