There are carefully crafted combos out there using GT40P heads, the Explorer/Mountaineer intake (with the lower ported) and a free flowing exhaust that put down 280rwHP/330rwTRQ with the stock HO cam. Different valve springs are generally recommended. And you have to be careful with header choice to clear the plugs. But by the time you've gone through the heads, I think you're better off picking up the better flowing aluminum heads from AFR or TrickFlow. Lots of those combos easily exceeding 300 at the wheels. And you drop 50 lbs. off the front end. Mine was originally put together with an Explorer intake and FRPP aluminum Y heads. I had the lower intake ported and replaced the Y's with AFR165's. HUGE seat of the pants difference.
