Increasing the clamp load on the cover assembly is a common way to get more torque capacity from your clutch system. It involves increasing the load exerted by the diaphragm to clamp the clutch disc between the pressure plate and the flywheel. The amount of clamp increase is limited as this can make the clutch pedal feel heavy and put strain on the clutch actuation system (hydraulics or cable ect.).
Clamp load increases can be found in the following upgrade/performance ranges, CI Heavy Duty, 4Terrain and Mantic