I have a JDM ZC and I am doing some pretty major renovations, such as new pistons, rods, rings, and the like, also while I have the engine torn apart I was thinking about getting the head ported and polished. It's pretty expensive but I want to know if it would be worth the money to do it or will the gains be to few to warrant the money? What kind of gains can you usually expect from a port and polish job.