New stall clutch. Clutch slipping now?

I only have 26" tires so I went with the EPI Economy stall clutch springs. I installed them once I got the case off and put everything together and put fresh oil in and violent fired her up and hit the throttle and I can hear the clutch slipping bad. I put everything in the exact way it came out. Or did i? Idk! If I did could this be why the clutch is slipping? Help!