Whenever I press the accel. down, I hear a faint, high-pitched whining sound that sounds like it's coming from the back. Could that be the fuel pump? If so, does it need to be replaced or is there a way to dampen the sound? I know that the previous owner had an aftermarket pump, but the dealership I bought the car from restored the OEM fuel pump (or so they tell me). Hopefully their install was sound.

Any ideas, suggestions?