Found this on the internet and have heard of racing teams using similar. Does anyone know anything about it?
ALTERPOWER
Though strickly speaking the alterpower is not new, I feel it needs to be brought to peoples attention as it is the best value performance increase per £ spent at £125. It works by stopping the alternator from charging at full throttle only, just when you want maximum power whilst accelerating. Most people do not appreciate how much power an alternator absorbs and one of the best things about it is that becuase most cars have similar alternators and equipment fitted to the car, the performance benefit is proportionally bigger the smaller the power of the engine, as the saving is the same regardless of engine size. EG. Say 8 bhp (at the wheels not flywheel) will be far more beneficial to a Saxo VTR with 70 BHP at the wheels, than a BMW with 200. We tested a Xantia on our rolling road, the minimum gain was 5 bhp and the max, with the lights, heater, heated rear window etc was 12 bhp. The point is, it is a conversion that you can feel when driving, not one of these, "I think it is better than before" jobs.