If the engine is still relatively new, it will get better with more fuel through it and further tuning. I don't know the pitch of the gears, available for the XXX-NT but gearing also plays a definite role in the hole shot as well as overall top end speed. Play around with the gear selection (Pinion and spur)to get the speed and hole shot needed.
As a rule of thumb, a quicker hole shot will give lower top end and vice versa. There is a give and take but somewhere he will find a good compromise.
Pipe selection also plays a part in performance. A shorter pipe will be tuned for more torque, a longer will be tuned for more speed. I may have the pipe info turned around the wrong way, but I'm sure someone will correct me if I am wrong.