I gave mine some stick today after it had heated it up and the amount of steam?!? that came out the exhaust could have totally obscured any car that was behind me's view.
I'm sure that it's just steam/water, water lying in the bottom of the back box.
It's not smoke or oil as there is no smell.
Just wondering if anyone else's does this. First time mine did it i sh*t myself as i thought my head gasket was away.