I would suggest exhaust, intake, and headers before touching cams, ecu, and such. The Honda Prelude actually gets some great gains from an exhaust system unlike other N/A engines. Save the computer modifications for last, so you can tune it and leave it be for the most part. Otherwise if you mod the computer first, every time you add a part you're gonna have to go back and re-tune the computer in order to maximize the gain out of the car from the added part.