Hi Andrew, Did you note any difference in blow by / crankcase compression on the two engines. Had a chance for a run down the road and a visual on overrun smoke? As before, it seems to be across the engine not just 1 or 2 cylinders - Bore finish, ring scuffing, valve seals, cam timing? I agree I think you have reached the point of a strip,inspection and measurement. Maybe a head swap to identify the issue Dave