+1 Hillrider
I have a Profile SBC fork(carbon steerer) that came with thier Gap cap, a compression plug supposedly designed to work with carbon. Ended up driving a star nut into it to get the adjustment to hold since everything else was correct. Follow HR's post on steerer gap first. As for torque, consult the manual or call tech service. I want to say that for Profile their spec was 65-85in.lbs. around the carbon steerer. Yes, they advize against a starnut in a carbon steerer(warranty void) but the composite plug was slipping constantly so... No sign of trouble after a season.