*NOTE* PLEASE MAKE CONTACT WITH US ON STOCK LEVELS, COMMON SIZES USUALLY ALWAYS IN STOCK, BUT NOT SO COMMON AND OCCASIONAL STOCK RUNOUTS COULD CAUSE DELAYS ON SHIPPING ORDERS. DESCRIPTION Once you have a GripTec pulley on your Trackhawk, a boost change is as simple as changing the outer pulley drive ring. All boost level changes require the appropriate PCM revisions and the proper supercharger belt. Please note that quoted boost gains are approximate, and that your results may vary. The 2.85" pulley is intended for street applications, while the 2.75" and smaller pulleys are intended for race applications or applications using supplemental injection.  Additional Information  We've found that the Gates K100572HD belt works well with the 2.75 and 2.85 pulleys and stock crank pulley (15-16psi). This part is available in our webstore. We've found that the Gates K100594HD belt works well with the 2.75" and 2.85 pulleys and ATI Crank pulley (17-18psi). This part is available in our webstore. We recommend purchasing the Hellcat Crank Pin Kit and completing this installation with your upper pulley upgrade. This part is available in our webstore. Custom tuning is required. Contact us for more information.