My 2 cents, low comp pistions. HKS turbo and tune. Best bang for buck for d series. Anything dseries in interchangeable, heads gearbox's and so on. If your planning to stay na b18c2 ur best bet cheap and better torque from teh hillclimb. I still reckon dseries turbo will be the best that torque increase is beautiful. I would get the double over head cam non vtec head and turbo it.