Car has a little over 50,000 miles.

Whenever I accelerate and even let off the gas pedal, there seems to be a whine that follows the car (almost like an R/C car). It goes with the engine almost.

Also when I shift my car into 3rd gear (its a manual), after about 2.5 RPM, I hear a high pitched sound that continues with acceleration, but stops when I let off the accelerator.

Any clues to what may be causing these problems? I just got the car and there seems to be nothing wrong with it, got it checked out with a mechanic and everything.

do you have any sort of turbo? do you have a lack of power? or a boost in power when you start hearing the whistling? do you have a cool air intake or a special racing air filter? what kind of muffler? and pipe? give me some information and a little time and i can figure it out