Need a better clutch

Just before I got snowed in I built a set of leaf springs for the duster that really hookup. I noticed that my clutch was now the weak link and started sliping. I have a elcheapo diaphram unit in there. Has anyone just replaced the disc with a dual friction type and what were the results? I need more holding power but I'm not prepared to spend 350+ for a cluch right now. Anyone have any experiance with just changing out the disc to increase holding power or do you have to have a higher pressure presure plate?
Lets hear you combos.