Swapped out my stainless Abarth 4 tip for a "Vintage Speed" Sports exhaust.
The blue smoke on start up is a good sign with a Shorrock Supercharger...it means the oil feed is getting to the front and rear bearings. The reason for the smoke is that on shut-down the oil pools in the intake manifold. When you start up this excess oil is injected into the chambers along with the air/fuel mixture and is burnt off.
Quieter than the Abarth, very nice deep thrumm and breathes better for a supercharged engine.