One of the main things necessary to set up a tuned engine is a stronger torque spring.

Torque springs are placed behind the clutch to press the rear pulley to the drive belt. If the spring is too weak, the belt will slip and accelerating becomes impossible.

Please note that using a stronger torque spring changes the variator set-up and you may have to insert lighter or heavier variator weights. One of the plus points of this spring is that the strength is printed on the spring itself!

White = +1000 rpm
Black = +1500 rpm
Blue = +2000 rpm

Motoforce MF84.101