Before you go out and buy something ask yourself it the present setup is slipping. A 'heavy duty' clutch is a disc with more stuff on it and stronger springs. That gives you more wear under slipping conditions while you engage it. What you really should consider is a strionger pressure plate. The thing that keeps the clutch from slipping is the psi on it. A high pressure / heavy pressure plate is the ticket there. Example - I had lots of luck in the good old days with a 6 cylinger truck clutch (smaller diameter but thicker) with a high horsepower small block chevy pressure plate on my old chevys. 11 inch PP and a 9.5" clutch. Could really dump off the line and never even get the clutch hot. It just got your knees because in them days it was mechanical linkage only. Lots of pedal push. With hydraulics today,,,,Just a thought from an old geezer