Originally Posted by tibra1
Care to comment why reputable CNC shops have invested time in the mounts and not the bolts, when the bolts are far easier to machine
Most companies that you are referring to are machining new bushings to improve feel and performance of the car, not for component failure.
BMW Group-N bushings were not developed to prevent failure, they were made for performance improvement for racing by increasing drive-train feedback, reducing and practically eliminating deflection to prevent alignment change while the car is dynamic.
Yes, machine solid mounts will help the problem and minimize it through reducing bushing deflection. However, this does not solve the problem, it alleviates it for the reason just mentioned.
Just a little fact about R&D in regards to this matter, creating the solid differential bushings through Solidworks and having them machined is an easier task than making new hardware. Now if we are talking about the actual sub-frame bushings, that's a different ballgame, however, hardware failure for the sub-frame is non-existent and you will probably never see new hardware being developed for that mounting point.