5.5 rollers or Ninja Sliders OR 7 gr Dr. Pulley Sliders.
I like the Malossi RED spring for the rear (equal to a 2000)
Those CVT kits are generally trash. I would get either a Jasil (top Racing) or a Polini Variator, and a Malossi Delta clutch.
Reality is you don't really need those CVT parts unless you go to a Big Bore kit, pipe, carb.
The roller/slider/spring swap will get you 40-45, and great up hill by them selves.