UR pulleys on my ole' Sentra SE-R made a noticeable difference - improvements throughout the rev range. I am about to install the ShoShop crank pulley on my Taurus to try for better low-end. (It doesn't do away with the stock harmonic balancer, so shouldn't have much of an effect on crank harmonics.) My SVT-C is stock, but I'll probably slap on the pulleys, before long. (Those stock pulleys need a good slapping, every once in awhile.)
