If you plan on keeping the car N/A I highly recommend doing a P.I head swap it is hard to get power out of these motors with the NPI heads. If you really dont want to spend much money you can do like Road Rage said or you can even do a P.I. intake manifold with the NPI heads(just make sure you use a NPI gasket and you get a different coolant hose) and you can pick up a set P.I. cams for cheap aswell you should easily pickup 15hp with less than $250 spent.