hey,what i did was i hung my pass side muffler, took it to a shop and had them fab everything else. they made the left side pipe and just cut out the y and used the existing right side one. Then i took it to another shop ad had them fab up my h pipe and it sounds great!

go to the exhaust sticky on top of the 4.0 homepage and you will be able to hear mine.

oh yeah i let the shop handle the bumper cutting and it looks dam good.

 

Good luck will make a big difference if I were you I would just buy the gt back bumper its like $180 at www.v6mustangstuff.com