Originally Posted by InfiniteVTec
There is a dyno difference with the UR pulleys, depending on the model of the car. You'll gain some hp and torque out of having pulleys, there's not drawbacks, only gains all the way across. I gained around 5whp with just the Underdrive Crank Pulley. I bet they'd work best with Superchargers. I recently bought a p/s pulley, all i need is an alternator pulley and i complete my set. They're nice under the hood too.
this is utter and complete dogshit...and yes there are drawbacks to underdrive pulleys...changing the diameter of a pulley greatly increaes wear on parts that were designed with a different pulley size intended to spin them within a certain range. Also the underdrive crank pullies manufactured are nowhere near as well balanced as the stock pulley. You can end up doing alot of damage. Also this claim of 5whp from an underdrive pulley is utter and complete bullshit.