Originally Posted by tabetha

Very wrong, it cannot affect the bhp in anyway, don't listen to this yank shit that they normally spout.
It also doesn't "make" the engine rev freely, it helps as there is less rotational mass to accelerate, so less power is used up during acceleration of the engine/flywheel, but it has a major effect on engine liveliness with a good amount removed, as the engine will "see" a much much larger load lifted from it than the weight would suggest.
tabetha