With a good alignment they really don't do much. I've also seen "drivesavers" not blow apart and "save" the drive when a customer hit some floating line. Drivesaver was perfect but the gear, prop & shaft were all toast... That said I do feel the PYI unit is better than the DriveSaver but still not a fully necessary item. I've also seen them cause more harm than good when installed incorrectly as they slide the shaft aft (not on a v-drive) and can actually cause shaft whip to exacerbate. On a v-drive, like you and I have, they move the shaft forward so if your shaft has the proper 1X diameter offset from the bearing then you'd likely need a new slightly longer shaft $$$$$...