5% or 10% OD SC pulley

I don't know which size overdrive supercharger pulley to buy. All the modefications that I have done to the engine are a cold air induction system, mufflers, and the resonator removed. I don't want to risk really screwing my engine up, but at the same time i want to get the safest ammount of power gain.

5%. unless you have replaced the entire exhaust system with an upgraded system (headers back) and have done at least a double IC, you're going to blow headgaskets and basically just blow a lot of hot air around if you get the 10%