Again I'm not ripping on UPR's products and I think they have a place and a purpose if you intend on building a quarter mile/eighth mile drag car. However, as someone who owns a car that is driven primarily on the street, I don't understand why anyone would choose UPR over MM unless it was due to the price difference.
I've had first hand experiences with 2 very similar cars that had very different
suspension setups. One car had MM
LCA's and a TA and the other one had a UPR 4-link. There's absolutely no comparison the MM
LCA's + TA provide much better control and handling than the UPR 4-link does. There is also less of a chance of experiencing snap oversteer with the MM set up described in the previous sentence due to the corrective nature of the TA combined with the compliant factory UCA's.
Now if all you like to do is launch hard and drive straight by all means buy UPR stuff. In fact that's what is designed for. UPR doesn't even sell Bilstein's, but they do sell strange adjustable shocks... why do you think that is? Could it be because they know they build and sell products that are best suited for drag racers?
As far as weight is concerned, you're right some of UPR's
suspension components don't weigh as much. Again, to the drag racer weight is the enemy which is why their components are light... OTOH road racers prefer to have components that are strong enough to handle the rigors of running through an autocross or road course. For me, it is an added comfort knowing that my MM
suspension components are over-engineered w/ no compromises. If I ever get in an accident the strength and integrity of these superior components may save my life.
OP, take these comments for what they're worth and make your decision based on the feedback from everyone here. I think there are good arguments for both
suspension companies. However, I enjoy driving a well rounded car that can handle and launch well, and still maintain very good road manners... therefore I'll choose MM
suspension components every time