New ultra-high boost 69mm pulley for Roush and VMP supercharged 6.2s. 11-12psi. Great for trucks running at high elevation that just can't get enough. Recommended to use with the stock belt and a VMP 90mm idler. 93 octane minimum with fuel pump booster This pulley put our crew cab raptor into the 12s at 103mph with a 1.7 60ft! Heat exchanger upgrade recommended when use in hot climates or when towing. Recalibration required to prevent engine damage. Gates K061251 belt will work in leu of Roush belt but is tighter, will not work with stock Roush 75mm pulleys.