I am currently running a Stage 2 in my 2001 and was also missing the turbo silencer ring prior to installing the Stage 2. I don't notice much more turbo whine with the Stage 2 (coming from a stock airbox), but there is a much deeper rumble coming out of the engine, especially under load or acceleration. I know I enjoy the sound much better than the stock airbox. The engine felt a little more responsive just not necessarily more horsepower.