Shannon Halbert at GoFastHp has several to choose from and is one of the best clutch builders in the industry, customer service is top notch also. His clutches are winning races every week, all across the country, you wont be disappointed I can guarantee that. He has something that will fit everyone's budget, and also offers fully rebuilt used clutches as well. His new 2 disc are as cheap as some of the more expensive single disc clutches out there and are just as good quality if not better, and his 3 disc are priced about the same as some of the more expensive 2 disc clutches out there. Can't go wrong with Shannon's work! Generally, the more horsepower and heavier weight of the kart, the more discs you would want. Single and 2 disc are usually used in JR classes and stock classes, 2 disc is the main ones being used for adult stock unrestricted classes, 3 and 4 disc are normally used on high hp open/RWYB karts only but some super heavy and sumo heavy drivers use the 3 disc as well. More discs means more weight on the crankshaft, which is why most prefer the 2 disc over the 3 disc for the adult stock classes. Hope that helps