I have a 2002 Subaru Wrx, no mods or anything i know of. I noticed a noise almost sounding like its releasing air/pressure, generally when on freeway or gas is being applied, not just low speed. I believe its only when the A.C is on but maybe not. Also, it screeches when the A.C is on, assuming that belt needs to be changed? Any ideas on the other sound, of releasing pressure?