Has anyone who's installed an underdrive pulley had a before and after dyno test done to see what the actual hp and torque gain is, as against the gain claimed by the people who make the pulley? I'm seriously thinking of getting one. I've heard the manufacturer claims and the butt dyno claims, but I'm not going to get one unless there is a true significant gain that makes it worth the money.

 

Wayne (graniteguy) did. I not sure but I think it was like 8 RWHP & 10ftlbs of Torque, check his site http://www.underdog-performance.com