I have an 04 WRX wagon, pretty much stock except a cobb catback that the guy I bought it from put on it. I has developed a strange ticking (loud but does not sound like metal on metal) that only happens as I let out the clutch under hard acceleration. It will continue for a little bit after the clutch is fully out, then stops. It does not seem to get faster with RPM but continues from about 3k-5k then stops. It does not happen under normal acceleration except occasionally when I am turning from a stop...Any ideas would be greatly appreciated.