Most people get clutch slip because they drive incorrectly.
Adding the extra power and torque means you can get similar levels of acceleration say in 5th gear as a stock car would in 4th, so people dont bother using the gearbox correctly and downshift as they should and instead rely on the torque to pull them through. WOT pulls in high gears from low rpm destroys clutches as it subjects it to peak torque levels for prolonged periods. I never had any clutch slip in my Focus ST, Octavia vRS, my current fabia or any of my other vehicles all of which have been tinkered with, tracked and abused because I change down gear when i want to speed up.