Maybe peak, but ITB's increase torque everywhere throughout the whole rev-range...plus hugely increased throttle response...they make a massive difference to the way the car performs.
Fuel cut off is usually used on road cars to prevent hessitation (when you come back on throttle) due to fuel collecting on over run.
The ecu will liekly have the function to enable/disable this...depends how its been set up really.
Glad you are impressed Richard.
They are 175+vat for me to work them if you send your spares/originals down.
If you want any more info, please email me info@ap-developments.com.