On my '01 mxz 700 I have an epi clutck kit. If i out more preload on the secondary spring what will i gain and lose? The emgine will spin at 8,300 now.

from what I was always told you lower rpm's with primary , not by tightening the secondary.I would add more pin weight or change spring first.assuming your not slipping the secondary.

I'm not looking to lower the rpm's. I was wondering what it will do for my upshift and back shift if I go 1 hole stiffer with the secendary spring. (will it get to top end faster, and what will it do to my backshift?)

If you put more preload, it will upshift slower and backshift faster. You may find it revs higher, then settles down to 8300, which is too high for your engine.

Start by setting your primary clickers down by one to get your peak RPM down to around 8000. This can also be accomplished by increasing your pin weight, which will make your sled upshift faster.

If your RPM's don't reach 8000 right away, your preload is too loose. If your RPM's go much higher than 8000, then settle to 8000, your preload is too tight.