Well, i have a little 306 with stock crank, and rods, and Probe forged flycut pistons, mac long tubes and prochamber, flowmasters that are dumped, edelbrock rpm air gap intake, holley vaccum secondary 650, and only running a water pump and alternator on the front, and electric fans. i was running the stock heads with this setup and a ford racing B303 cam with 1.7 rockers and a 150 shot of nitrous and i dynoed in at 409hp and 537 torque to the wheels. well i just bolted on these patriot freedom heads and without any tuning i can feel a huge difference. i did have to fly cut the pistons to clear the 2.02 intake valves. it feels like the stock heads with a 100 shot of NOS. but tomorrow i will put the car back on the dyno and see how much i picked up. without nitrous the car was making 287hp and 302 torque. the heads are actually beautifully built and machined, but i dont know how good the valvetrain is going to hold up.