Powerflex Upper Gearbox Mount Insert PFF85-441BLKPFF85 441BLK uses our stiffest Black Series 95A material, providing a no compromise performance option for track focused builds. A small increase in NVH, usually at idle, should be expected when stiffening the connecting mount between the drivetrain and chassis. The harder the material used, the greater the NVH transmitted. Reducing engine trans movement by way of upgraded inserts has the following benefits Sharper throttle response More accurate gear