After much experimentation with the stock (Italian version) carb, OS carbs, ASP carbs, I put a Perry (Conley) non-pumped Mega carb on the ST-2300. Bisson Pitts muffler with one outlet blocked for tank pressure, OS-F plug, APC 17x8 prop. Ran Cool Power 10 to 25% nitro. Engine runs superbly, never quits, excellent throttle response, linear and excellent power. Sold the engine and plane to a novice flyer and instructed him not to touch the needles on the carb. He followed my advice and flew the plane for a season - excellent power and not a single dead stick for him. The higher nitro fuel makes more power, but had no downside other than cost.