so i just bought my first Audi its and 2002 Audi a4 1.8t and i need to replace my catalytic converter. can i just buy any converter that's a bolt on. and just use that? or is there any sites that you guys might help me with.

 

u can run a hfc or test pipe. But be aware if you live in a place where they are strict on emmissions that will cause a problem.