As much as I love Pypes Violator muffs, **DO NOT** BUY THE PYPES X-PIPE!
The lack of tranny crossmember hangers causes the rear-end of the X-pipe to sag constantly, especially on cat'ed X-pipes. I have (or rather, I had) a UPR cat'ed X-pipe with the exact same design as that of the Pypes X, and not only did I have the sagging issue constantly, but the cats were welded about an inch or two too far back, so that I had to cut a notch out of the tranny crossmember just to make them fit up in there without banging against it all of the time.
FWIW, a couple of folks have had issues with the fitment of the Pypes cat-back, as well. There's a thread about it in 5.0 Tech recently, I believe.
Myself, I had good luck with just buying the Pypes Violator muffs, alone, and swapping out the Super Turbo muffs from my Dynomax cat-back - their tails are stainless and bent/cut in such a way that they don't have ANY fitment issues, really. Although, I did buy the early form of the Violators when the first were exhibited at the WFC vendor area, $80 a pair, and they were 2" longer than the current ones - I wound up having to cut 1" off my tailpipe and 1" off my flowtubes to make things fit together right, but it came out well enough. (Driver's side tailpipe is still about 1" too long, but at least things are level and don't knock/rub on anything.)