1994 Mustang GT 5.0L Standard trans, EFI, OBD-II After the following modifications, it is lacking power: GT40 intake manifold 3/8" spacer, GT40 Alum. heads 65MM throttle body 73mm mass air meter 24Lbs injectors 1 5/8" shortie headers, E303 Ford Motorsport roll... Login to read more.