I just installed some clutching that included a 143/285 primary spring. I'm runing cat 73 gr weights, 48/36 P helix, shift assist, stock orange secondary spring, AMP deflection adjuster. My clutch engages at about 4100-4200 RPM which is supposedly correct for the kit, but I would rather lower it a bit. If I put the stock yellow/white spring back in which is a 122-285, it should lower my engagement - right?, with the same 285 finish. My question is - what are the drawbacks to a lower engagement and why would a performance clutch kit include a spring which only has a higher lower number - same finish - and therfore raises engagement? I top out at about 7800 RPM which numerous people say is what I should shoot for - 09 M8 SP, SW y-pipe & can, stock pipe. Others say 8000 RPM? I just bought Cutler 65-75 adjustable weights in preparation for my winter sleddig trip and want to take the primary apart one time only so I now need to determine the best spring. thanks