More power
#21
As stated the only way to squeeze more power out of it would be to get a better set of ported heads or juice. Generally though if your going to the effort of swapping heads you have everything apart and it would be wise to upgrade the cam to some bigger to make more power. Its a chain reaction and really up to how much he's willing to spend and his goal for the car.
#22
Swap out to a 224/236 AI cam. Stock heads a guy laid down 370whp. Get the heads ported by AI to the 200cc and you'll be laying down some power. Plus the intake manifold Street/strip port by AI, bigger throttle body. That's it besides stroker or boost or juice.