I did this on my Civic Si, I used 4AWG and 8AWG. It has been proven on the Si board to actually make a difference on throtle response AND your lights get brighter. Not sure if it actually makes more power though.
Greg ZTS2 upgraded my grounds for me this weekend, we did the one just to the left side of the motor, and the negative cable that attaches to the battery. We used 4ga wire, and My lights don't dim and the car feels like it responds a little better. I also installed a Red Top battery and a coil pack with livewires too, which may contribute but it feels a lot cleaner now....Peace
Well I did the over kill thing. I had extra 2 gauge from the stereo stuff that I am installing. (Yes 2 gauge is over kill for 1 amp, but who knows what might happen) So I upgraded the 2 so far, and plan on doing adding a few more, but less gauge more like 8, 0r 10 gauge. I just figured this is one of those old school tricks, that some ppl forget about.