Just installed the Pypes xfm26 X pipe with hi flow cats. Easy install but plan on having some pieces welded later to get rid of exhaust leaks. The primary issue was where the passenger side down pipe connects to the cat. Even torquing the clamp down with an air gun couldn't get rid of it. I had the local muffler place weld the down pipes to the cats. No more leaks.
As a note, if you just install the xfm23 off road x pipe you'd have no problem at all.

 

Ive had leaks with all pypes products! anything that clamps together will leak sooner or later(especially the cheapo clamps pypes supplies) welding is the only solid solution. how much louder are the pypes cats?

 

Part of the problem is you're cutting the "off road" pipes to now make them the street legal catted versions - this spooked me a little from the beginning. On the pass side this means you're connecting the cat where the pipe is beginning to bend...not good. Anyway for $335 + $20 in welding, still a great value.

With the combination of the Pypes X/cats, JBA shorties, and Flowmaster; it's not really "louder" per se but it has throatier, more aggressive sound that is growing on me. I was just able to hear what it really sounds like yesterday because it was leaking for a week.