We highly recommend the RPS and McLeod Clutches and have used these to great levels of success.
Current pricing as follows:

RPS - 28 lbs. Single Carbon Lite Clutch. 600 ft/pd Torque Cap. C6 Applications - $1295
RPS - 39 lbs. Street Twin Carbon Clutch. 750 ft/pd Torque Cap. C6 Applications - $1795
RPS - 32 lbs. Street Twin Lite Carbon Clutch. 750 ft/pd Torque Cap. C6 Applications - $1995
RPS - 32 lbs. Billet "Strapless" Twin Carbon Clutch. 950 ft/pd Torque Cap. C6 Applications - $2595
RPS - 36 lbs. Billet "Strapless" Triple Carbon Clutch. 1150 ft/pd Torque Cap. C6 Applications - $3495