FWIW, I put a lot of UPR pieces on the '89 notch that Frankenstang now drives, and I had mixed results with their stuff. Their billet stuff is good, such as their wiper delete post covers and shift knobs and such, and I've favored their clutch cable firewall adjusters and quadrants, but some of their mechanical items are ... ehhhh, so-so.
I absolutely HATED that damned cat'ed X-pipe I bought from UPR. The cats were welded too far back, the whole thing hung too low no matter what, and the lack of tranny crossmember hangers made the thing constantly sag at the rear flange, meaning I had to jack the thing up and re-tighten it every two weeks. I only kept it around for smog testing after I swapped it out for a Jeg's off-road X-pipe, which was cheaper than UPR's off-road X-pipe and designed FAR better.
Also, I wasted $75 on a friggin' A/C delete pulley from UPR. Ideally, I would've just used an A/C delete bracket to move up the P/S pump, but I wanted something to use as an idler pulley when I planned to delete the P/S pump and convert to a manual rack at some point (which still has never happened). After 6 months, the friggin' bearing in the pulley wobbled itself out to a point where I worried it was either going to throw the belt or the bearing was going to separate completely from the pulley. I replaced the pulley with a smaller idler pulley (which was actually meant for Frankenstang's '04 V-6 'Stang) and a shorter belt, and re-used the bracket of the UPR A/C delete assembly, and it still works great, but that bearing issue really pissed me off ... especially considering I paid so much for just a friggin' pulley and a bracket.
Sooooo, it depends on what you're looking for from them. Some stuff good, some bad. Look closely at how the piece is designed, and search for any good/bad reviews of their stuff from others on here. Ditto for MM's stuff ... although I haven't yet seen any really bad reviews on their parts, aside from FBD's less-than-happy experience with their roll cage kit being like 1 or 2" too short at the rear. You'll pay more there, of course, but sometimes ... SOMETIMES you do get what you pay for.