I'm the original owner of a 2001 normally asp forester. A low end sounding knock has developed at 100k miles. Comes in under load at 2K rpm. Comes from the right side of the car. CV joint seems tight. Oil is clean and no metal in the filter. Power is good and no other eng perameter changes or CEL. Any history of exhaust baffle or leak issues with these cars that could fool my ears?