has anyone used one? do they jack up your engine? from what i understand the stock rev limiters usually cut fuel resulting in your car running more lean which can result in detonation therefore are bad for your car. but ignition cuts out spark but wouldnt that mean you have unburned fuel releasing into your exhaust and if you're turbo wouldnt that mean you are sucking unburned fuel into your turbo and isnt that also bad? i'm looking into a bee*R unit and i want to know if it will jack my engine up to get one?

To be honest, I'm not sure how much it would "jack up" your engine, but just throwing fuel through it is not good for anything. The stock rev limiters usually cut fuel or both, which is ideal. You are however correct, that on just fuel cut revlimiters, they temporarily cut power to the injectors (usually half of them) so there is no fuel in the cylinders, but running high boost levels could result in holes in pistons. When you just cut spark, the fuel is injected, but the coil pack cuts spark so you presumably have an unburned mixture (provided it doesn't detonate) which on a hot engine will foul the plugs quite badly, and when it hits the hot gasses in your exhaust mani, it will ignite and send your EGT's through the roof. Alot of the time this manifests itself in the popping you hear in the exhaust, which is not anti-lag, despite what many say. To be honest, neither are good for the motor, and the best way to go about rev limiters is to do both spark and ignition cuts.

Bob