9. Belt slippage is a big problem with high-boost applications and to remedy that issue before it started, we upgraded all our pulleys to 8-rib pieces. The conversion (p/n 917339) is from ATI Racing and includes a race-certified harmonic balancer/crank pulley. We first pulley the original crank pulley and replaced it with a stronger and wider unit from ATI. This is the back pulley, which controls the A/C belt. It needed to go on first and with a new crank bolt used, was torqued to 240 lb-ft.