I can tell you from what i delt with is you either need a larger crank pulley or convert to an 8 rib pulley set. I couldnt get my car over 9lbs on the 5 rib and I had to run so much tension it hurt the bearings in the SC.
Call ATI they have a Larger Pulley-Dampener the drawing number SK219B1
This is a 8 rib all the factory locations were maintained. I had this designed for the same reason. This produced 29PSI before I got my top pulley corrected with my 2.9L Whipple SC. Now I have it set at 19PSI. I will most likely drop it down to 15 PSI soon or just put my boost controller back on. with the boost controller you can raise or lower at any time from the cockpit. Ken