You probably won't notice any change in noise levels. I didn't have to retune the engine, but it is ridiculously easy if you have to retune. The engine is extremely forgiving if you don't hit it just right. A lot of people say you don't have to retune OS .46 FXs, but mine barely runs without the baffle. I guess it depends on each engine.

Dadstoysbg, are there 2 prop drivers for the Evo? I'm having the same spinner problems as Righty. The spinner back plate alignment ring is barely too small in diameter to fit over the driver. I didn't use it because I don't need any more vibration induced damage to the firewall area.