I have put heads (3rd run Cobra) and cams (Crower stage III) on mine. also added so many other mods that I do not know what the gains just from that are. Sorry could not be more help.
My motor is being built right now. The heads arn't getting ported because I've heard that its not worth the gain for the money. But the Crower stage 3 cam is going in the car for sure.