I couldn,t find this in a search.
I hear a lot about downpipes. What does it bypass and what do I need to install one besides the pipe only?

 

The downpipe eliminates the pre-cat allowing your turbo to spool a little more freely. You just get a good hp increase with it. The most common/popular ones that I've seen with 2nd gen owners are from:

www.racingbeat.com
www.corksport.com
wwww.thunderfabrications.com

Hope this helps.

 

Thanks I'll check em out.