Best GA modification - Turbo. Unfortunately you pretty much have to build your own "kit" these days, but leave motor stock, slap turbo on it with some injectors, MAF, and ecu and beat the shit out of it. If you blow the motor, a new one can be had for a few hundred bucks. Swap the kit over and repeat as needed. There are millions of GA's out there so these steps can be repeated almost indefinitely.