I would use as little torque as is sufficient to reliably do the job. On my MK5 I think the spec from Geissele was 35 ft lbs, on my MK8 I think it was 40 ft lbs. I have read that less torque is best for accuracy but to be honest I can't really see how torque would affect accuracy. I can see how over torquing the Geissele rail could easily strip out hardware. The tolerance between the barrel nut and rail are really tight, it doesn't take much.