My '07 G6 GT convertible (fun car!) has begun making a high-pitched rubbing/hissing sound when it’s moving and the engine’s running between 2000 and 2500 rpm. I hear the sound when the top or windows are down and I pass by other cars or am driving near a curb or a wall (the sound reflects off and back to me). I don’t hear the sound if the car’s not moving. I’m pretty sure it’s a sound made by rubbing, but very high pitched like the hissing of an air hose. The sound disappears above 2500 or below 2000 rpm, and sometimes when the transmission shifts so that the engine goes from above 2500 rpm to below 2000 rpm, I hear a little squeak as it goes through the 2000-2500 range. Anybody have any idea what might cause this?
Update–two shops have thought it was exhaust-related, but neither has fixed it. The first thought it might be coming from the exhaust resonator and recommended I take it to a muffler place. The muffler place thought it was coming from the endpiece on the tailpipe and replaced that, but the noise is still there. Any ideas? Anyone?
Update: it was the exhaust resonator. Took it to the dealer and they replaced the entire exhaust system past the catalytic converter. No more hiss!