Only go with the UPR X if you don't mind having to jack the thing up and re-tighten the rear flange bolts every other weekend. They don't have tranny mount hangers, so they always wind up sagging and then scraping on every little bump in the road. I only use my UPR X-pipe now for smog inspections; my cheaper Jeg's X-pipe sounds better (no cats, heh), fits great, and doesn't get droopy.
A few other companies sell X-pipes similar in design to the UPR model -
Pypes and some other place, I believe. Unless you can rig up a hanger of your own, or if your car only sees the road once in a great while, I'd steer clear of any X-pipe with their kinda design.
FWIW, the Jeg's X-pipe rocks because it comes in three segments, which makes it WAY easy to install - hang the downtubes, push the crossover section forward onto the tubes and tranny crossmember, and clamp it tight. Done. None of this crap of using a jack to hold up the rear end while you snug the front bolts and having the thing slip off and smack you in the face. (Been there, done that.)