Spring will not help top speed.
Putting in a stronger spring in the secondary clutch will help with belt grip and will raise the shift out RPM.
I'm not sure if a CVTECH clutch is available for your model but I put a CVTECH on my Sportsman XP1000 that has a Gear Reduction so it would top out at 65 mph and with the CVTECH it was over 68 mph and I don't know how many more because I had to let off.

 

ok thank you

 

Secondary springs are used to control upshift and back shifting. A higher rate Secondary spring will lose top speed, but it will raise peak rpm.

Only change the secondary spring if want to change how the machine back shifts.

The primary spring will also effect the secondary clutch, they work together to control the rpm through full shift.

For the primary I find a spring with the starting rate that I want for engagement, then I look at the finish rate of the spring, I never go high on finish rate, higher finish rate on the primary will also slow the top speed down.

Basically I prefer to run the lightest springs I can get away without sacrificing belt grip.

 

Basically what you said is right but the part about the higher spring rate in the secondary dosen't have any affect on top speed.
The over all belt travel and there is a limiter in the primary clutch and the CVTECH clutch does have more travel than the OEM clutch.