As steve says they all smoke to some extent... Mine was smoking black when booting it, and i was getting very black tail pipes and clumps of soot on the boot, though since having new plugs/fuel filter/oil change and the Revo tweaked from F7 to F8(which is leaner) it hasn't been smoking so much, tail pipe don't blacken as quick and just a fine dusting over the boot... You are always going to get some as it's a high powered turbo application and always better to have it set a little rich than too lean... no poke without smoke ;)
Jim at JKM says its normally... I was pulling no faults, burns no oil, probably put in 1/2 a litre in between services(approx 8000miles) and it's pulling strong...
I wouldn't worry about it, it's just alarming you've noticed it, i was the same...