I ran the same sled you have untill this year. This year moved to an M1000. But, before I moved on I did have to do some tinkering to get mine to keep up with the other brand 800's.
The sled should run near 7200 rpm assuming you have all stock engine components. Your rumbel pack and VForce reeds shouldn't matter (assuming the Rumbel Pack doesn't lose you horse power). Depending on the altitude you ride 62-66 grams weights will work. I rode Cooke City and used the 66's. When I was riding high 10500' + the 66's were a little too much; but when I was lower they were just right. The factory spring in the primary clutch work fine, but for you it might be time to replace the one you have, they don't last forever and when they lost their tension they effect the sleds performance ( your tach won't stay steady it will move up and down when you are wide open). The secondary clutch worked best with a green spring. It is stiffer than the factory and allows the the clutching to back shift better when your loading the engine. I had to change the gearing from a 19-43 factory to 18-44; the 18-44 worked well and I was able to use the factory chain thus less cost. Those were the only clutching changes I made. Mine ran near 7200 rpm consistantly wether I was climbing a hill or racing across a lake. But I still couldn't climb a hill as well as the other mfgrs. I was frustrated with it. As dumb luck has it I noticed that the factory track had lugs that bent over like the Attack 20 lugs. They were soft and pliable. Not good for hill climbing. So I decided to change my track from a 151 to a 159 and bought a Polaris series 4 type track (tracksusa.com). It had stiffer lugs and they were 2.25 in instead of 2in. What a difference! The thing climbed right with the others no problems.
Two weeks ago while riding at Cooke City I ran into two friends, they had a 05 King Cat and a 03 159 900 EFI Mountian Cat. They too had changed their tracks out to a Challanger Extream and a standard Challanger respectivly. They were both grining ear to ear and they like me could not believe the difference in how they could climb a hill.
My 2 cents, hope it's good for you.