I am looking at some catback systems and the one I was considering was the flowmasters catback found here now is any x pipe compatible with this or what? Also what mufflers would come with this, the 40 series? And lastly, would you suggest an x-pipe or an h-pipe?

 

either or, Both will allow the banks to run equally. If you do go with X or H make sure you get them with hi-flow cats or you may loose backpressure if you dont have a power adder.