The only electric I know of, if I remeber correctly, was good for maybe 5% increase in horsepower. I honestly think even 5% is a stretch for that manufacturer.

The best route to take would be a supercharger or something from Vortech. If they ever take the time to make something for our cars.

The next best thing would be a real Turbo or twin turbo setup. Hell I would even consider swapping out my pistons for a lower compression set just to have the chance to add about 15 to 20 psi of boost. That should be good for a few extra ponies.