I do not know Club Car but have done the following on my Yamaha:
Spring (POWER KIT)
Having changed my primary clutch from an original to a performance one sold by CPP, I was suggested to change at the same time the spring of the secondary sheave to counterbalance as they work together.
Perhaps it gave me more torque but I cannot say I remember a lot of difference.
Severe Duty Drive Belt
More than a year later, I had to change the drive belt and opted for a G-Boost severe duty. This belt is by far a good belt and my next one will be the same for sure.
This being said, I never noticed any signs of increased performance...
8:1 gear installed with machined Sliding sheave
I started a thread two months ago (click here)...
Concerning your topic, I replaced the machines sliding sheave by the original one and cannot really notice a difference in torque.
May I insist on the fact the region is really flat, so perhaps it could be different in another region...