The vented flywheel will not work with the pro mounts. The flywheel does not go back far enough so the clutch bell will line up with the spur gear. I thought it was just me but my local hobby shop sent 5 of them back for the same reason. The only way I see to correct the problem is to cut down the rtr mounts that you can slide the engine back or forward. This is just my experience , may not be everyones.