They "Pick-Up" the rear and GREATLY IMPROVE "turn in" in the tight stuff and on the track. My bike turns as good as most "modern" bikes AND BETTER than most 450s. No Crap!
They're worth the investment. The bike WILL sit a little higher in back. Get used to it. You're bike will loose that "Heavy" and "Sloppy" feel.
I'd, also, suggest an ACME or Pro-Circuit revalve. Both companies have A LOT of knowledge on K5s.
Go do it!
Manny