The MAC X is sold by Pacifica and is a good piece IMO. Mines been on my car for over 2 years. Fit's good, makes good power and is cheap. It looks very much like the UPR or VRS pipe....a true X
I've got a 2.5" O/R X-Pipe, and I love it. I got it along with my mac catback, and I like the sound alot. The X-pipe still looks fantastical, and has been on there about 5000 miles so far. Piece of cake to install, too.