A little different perspectice from a 100% duner with a 450R:
I have tried about 6 different geraring combos. I did not taske in to account how fast it got me up the hill, or time anything, just what was the most rideable. 13 tooth is too low for me. I think it was "faster" up the hll, but everywhere else, I was shifting more. With my current combo I can run 3rd all day, almost. I ended up with a 14/39. I run a 7 paddle 20" hauler. Buy a 13 tooth front, and a 37 and 39 for the rear, try them all (its less than a $100 investment, what can you do on a quad for less than a $100?).
If you are a sand oly guy, or at least a non water riding guy, ESR has a cool airbox eliminator kit, or PM me and I can get you a bigger one for about $80 (including a big K&N and outerwares)
Dune sliders and Sand stars are nice for duarbility, but the perfpormance is not up to Haulers. Everyone thinks Haulers are for hill climbing only, false. I have settled on a 20" on a 10" rim with 7 paddles, and I can whip it better than any other tire ( I have tried them ALL). You will have that MX tire feeling, good response, no sidewall to fold over on you either (better cornering), and Haulers are SUPER light.
Where are you from?