A new Super 8 150 is set up at optimum as it starts with 13 gram rollers in the CVT, and is balanced for takeoff and top end for a long time.
I got a used one with 5000 miles, and when I opened the CVT to inspect, there was only minor wear on the belt and drive face, and the rollers were still servicable for another 3-5000 miles at least, and maybe more.
The stock drive weighs 300 grams, so I put in a standard gy6 one that weighs 237, and went to 14 gram rollers to keep the RPMs down at WOT. Top speed is 63 MPH and 55 is comfortable.
I tried a 108 jet, but it seems to rob power by being to rich, so I replaced it with the stock 102 and left the stock 35 pilot jet alone.
Not much tuning is required, but if you care to, most gy6 parts will work, Keihin jets and 18x14 rollers, replacement belt is 23100 KEC4 9000