X Pipe Install??
 

I'm doing the resonator delete/x-pipe install next weekend myself. What are the advantages/disadvantages of leaving the factory flanges on there instead of just cutting?

this should get you started, just do a search:thumbup:
http://www.xoutpost.com/bmw-sav-foru...ipe-3-0-a.html

Disadvantage is potential leakage - be sure to mark the position of the donut gaskets that come out of the exhaust where it is bolted in the rear. They might be malformed from heat just a bit and not give as precise a fit going back in different sides or positions. These are $35 ish a piece at the dealer.