LOL @ 30bhp increase But I do beleive there is an American one called something like E-RAM which has been shown to give some increase on BHP on some cars. Most are based on air bilge pumps for boats or even worse bloody PC cooling fans

I should imagine even the "proper" E-RAM one would cause restrictions on almost any mildly tuned or above and quite a few standard engines. In short they're a total waste of money but you can't blame people for trying I guess