as a matter of fact, i talked to someone with that same system. He fired it up his 4.0 with that system for me, i wasnt very impressed.
I did research Pypes's website, i think i found a solution.
http://www.pysales.com/iwwida.pvx?.......
Seems like it will be perfect for my situation. With this, i should be able to get rid of the y-pipe and replace it with teh x-pipe. i can also use any GT axle back exhaust.
I want to make my 4.0 sound more aggressive. Does SLP Power Flow axle backs seem like a good choice?