ive got a fiesta rs turbo thats smokeing after about 1 min of starting up or when you blip the throttle its also smokeing out the breather kit even on tick over, its had new turbo, baily breather kit, and recent head gasket, oil returns ok, just done a compression check and number 3 was down to 50 psi, all the others were about 150 psi tried it again with oil down the bore, and it was still 50 psi, tried it with oil down the bores and the rocker arms removed and it was still 50 psi, all the valves and rockers looked ok from above would a damaged valve cause these problems or is it the rings shot??