I talked to a engine builder about gear drives,(He doesn't like them), but he told me the drive gear and the idler gear are free floating on the drive gears axle and will move in and out a bit. That's why some machining is required. He modifies the drive gear axle also. I'm considering using one mainly for the competion "sound", but I'm wondering just how loud and irritating it will be crusing at about 2,000 to 3,000 RPM?