Went to the local Rs meet tonight and on the way home every time I accelerated hard up through the box I had loads of thick smoke bellowing out the back. A mate following me said at times you couldn't see the back of the car it was so thick. He also said it didn't smell like oil and thinks it was black in colour.
Dropped my mate off then accelerated hard a few times when I had headlights behind me and no smoke at all.

If it was over fueling would this not do it all the time or could something else be causing it ?