Originally Posted by SteveAZ
I know you often get what you pay for, but they're both urethane, they both have steel inserts, and look very similar...the one thing I do notice is that it appears as though Prothane's front and rear bushings are two piece and Powerflex's front are two piece and rears are one piece?
Both designs have flanges top and bottom. I am not sure how you could install such a bushing if it truly was 1 piece. I found another image of the Prothane bushings that actually shows that the urethane is split down the middle. They appear actually to consist of 5 pieces - 2 urethane, 2 washers, 1 core.
This is splitting not only bushings, but hairs ...
The M3 subframe bushings provide an incredible improvement to the suspension and allow the front tires to actually work. As I have posted previously, the OE bushings provide passive rear steer, which forces the car into understeer near the limit and severely abuses the front tires. Remarkably there is virtually no increase in NVH with the M3 bushings. In short, the are excellent (if not perfect) on the 135i. When something works this well, I suggest looking no further.