I have had lots of 5.0 (pushrod) fox mustangs and many 4.6 mustangs. The 2 valve engines are okay but if you are looking for more power you are better off just selling the car and buying a 4 valve car. i have a friend who bought a 2003 GT convertible. He lives in the Detroit area. The car was in Georgia. It was a great deal he drove down to get it. He didn't intend to do anything to it but he ended up wanting to do more with it. My friends and I told him not to but he started buying all kinds of go-fast goodies for it. He changed the heads, the intake, exhaust, cams, throttle body, put a ProCharger on it, upgraded the drivetrain, suspension, and installed a cage. He wanted to autocross the car. We told him the bottom end was not strong enough to handle all the power but he figured he would run it till it blew up and then worry about it then. We he blew it up within a year of upgrading it at an autocross event. Unfortunately he threw a rod and broke the block. He then built a new short block with a nice crank and i-beam rods. The car rocks but he put a crap load of money into it and lots of time. He would have the same amount of power with a 03, 04 Cobra with a gear, exhaust, and a new pulley for the supercharger. I would just leave your car alone. Drive it. Enjoy it. Save more money and buy a 4 valve car.