Rogue comes with 2 pulleys.
1-pulley systems will have an effect on slowing down ALL accessories, but within safe levels both on the street and track. It's also cheaper to make, since it shares the same pulley as the S85 M5.
The 2-pulley system on the Macht Schnell systems gives the benefit of added power (actually freed up power), without any sacrifice. There's a couple of reasons why this method is chosen:
- BMW A/C clutch systems are designed to fully disengage at WOT, there is no need to underdrive that part of the system. IMHO, E9X AC systems are already weak in stock form, no need to further cripple it.
- Macht Schnell replacement belts are standard off-the-shelf belts that can be purchased from any auto parts store if/when needed. If you've ever tried searching for a double-sided 6-rib belt at an auto parts store, you'll know what I mean.
The MS pulley systems are priced comparatively with most 1-pulley systems, and a large number of them are used on the track. It's simply the best bang for the buck.