I went Delrin for the motor, trans, shifter and trailing arm bushings. Urethane for the Subframe bushings for the S52 TI. it does shake at low RPMs but at 800rpm,its smooth enough. Need to swap out the diff bushing before the season. Will prolly do the same for my AutoX Z3.
Rubber is definitely more comfortable and is perfectly fine for the M44s. I suspect it would be fine for the S52 as well, since I set this up to be used as my track car, I renewed all with the firmer/solid bushings to get shifting and road feel solid.
