I need help with traction.

Ever since I put in the grabbier spec stage three clutch, I have lost a bit of traction. Shifting into second, I can smoke the tires for about 30 ft at 60 mph, and the rear end can kick out shifting 3-4 at 80 mph. I have done a few mods to help with traction, all mods are in sig. Rear tires are 275/40zr18 kumho ecsta mx's and have plenty of meat left. Would Nitto 555's make much of a difference. Thanks for any help.