Ok Junkie now slip out there and check the timing again with a light and tell us just WHERE you have it set.
The smoke is OIL SMOKE! The hotter you get the engine the less you can SEE the smoke.. It is burning all the way into the exhaust pipe.
You indicate you "downshift" Does that mean that you do what semi's do and you actually SLOW the vehicle with a lower gear? If so that is when the engine is loading up with oil from the valve guides & seals.
Also the guides continue to drip onto the valve grinds while the engine is turned off. When starting again you have a "load" of oil to burn coming into the cylinders.. And it does not burn too good in a cold system. Hence the smoke. Then as the engine system including the manifold and exhaust pipe heats to optimum temp most of the smoke is burnt away and it is not seen..
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />