One can argue the pulley question from two sides. First there is a stright forward technical issue of elimination of the harmonic balancer portion of the crank pulley. There is one series Honda engine for which they have stopped selling pulley kits because the crank main bearing are particularly sensitive. Harmonic balancers are a needed component to protect, usually the front bearing of the crank from periodic vibrations that can occur at certain rpm in any engine. Over time vibrations can cause or aggravate wear. Do not bother to argue with someone who denies this fact or tries to tell you some story about how racing engines do not use them or what ever. Rubbish. You want to keep your harmonic balancer in place. Period.

WARNING: Some companies have been marketing replicas of UUC's original pulley design, but advertising them as superior due to "light weight". This clearly shows these replica manufacturers do not have an understanding of the underdrive concept... weight reduction is not a factor in producing power with underdrive pulleys... the gain comes from reducing the accessory speed, not from less rotating mass.

While some pulley advertisers do advertise "lightest weight", we feel that to be somewhat deceptive... in our extensive testing, we have proven that the actual weight of the pulleys is not a factor in increasing power gains whatsoever. Each pulley itself weighs just a few ounces... shaving off a small amount of additional aluminum will not make one single bit of measurable power. Weight savings in a BMW that are important are in the much larger rotating components such as a lightened flywheel or lighter road wheels.