Please see Innovators West 9% Overdrive balancer (Part # 330) as an alternative when the ATI is out of stock.� Comes with additional low profile installation hardware supplied by HHP so that you do not need to save the heads off your bolts. Use of this pulley requires custom PCM calibration/tuning. ATI Super Damper, SFI approved for street and race applications. Built specifically for high-performance applications, the ATI Super Damper provides balanced dampening of torsional crankshaft vibrations at all RPM while overdriving the supercharger to increase supercharger boost levels when combined with custom tuning that is needed to disable the factory overboost controls. The patented ATI Super Damper is the only damper designed exclusively for high performance engines. Eliminates torsional crankshaft vibrations Exceeds SFI 18.1 specs Laser engraved 360 timing marks Black zinc chromate finished Inner and outer shells are aluminum or steel to contain the steel inertia weight. The inertia weight has eight computer-machined grooves to retain the proper durometer O-rings (installed at ATI and dyno tested for each application). O-ring life has been tested in Winston Cup competition over two million cycles and in drag racing engines for 10 years (exceeds SFI 18.1 specs). Units can be rebuilt by installing new O-rings.