So my fresh engine had a few issues at first (too much boost because of wastegate linkage hitting IC pipe) but now runs strong, except that at about 500 miles it began smoking when backing of to a stop. Large cloud comes up and surrounds car. 7M GTE with minor mods--big intercooler, 3 inch driftmotion exhaust and down pipe, driftmotion modified oil pump, all new internals, and no smoke when first running 300 miles or so. Having someone follow me they say anytime I back off the throttle it smokes. About to change the oil so I will look for oil dilution, but AF gauge looks ok, so I'm thinking turbo seal? All ideas and diagnostic tricks most welcome.