well i made 400rwhp through a 9" and slicks on a stock 350 LT1 and a S-trim on 5-6psi running 24*. probably around 430 with street tires and a 10 bolt, if that helps you guage it any. there is no reason for a cog. a 8 rib pulley slips very little even when i decided to try 15psi