What he said ^^.

I think it's a HG, is the car loosing coolant? The smoke you are seeing is probably actually steam, take the oil filler cap off and see if you have "Mayonaise" underneath. This can also make the car idle lumpy due to coolant leaking into cylinder although as you say a aftermarket cam will also cause this, another thing you can do is examine plugs if one is not like the rest, I.E clean this is where that plug is effectivly being steam cleaned by water ingress in that cylinder.

Standard boost is 9PSI and that's on standard T2 turbo I would think you have a 195 chip which should run around 16PSI, the power claimed is where the 195 comes from.

Martin