Start with the variator Boss & jets for your best bang for the $'s. My wife's 2013 had a restricted variator boss 3mm ridge on the end, won't let it shift up all the way, changed it to a smooth one . The carb measured 16mm at the spigot, the manual calls it 17mm equivalent. I bought a 20mm for the 72cc big bore I installed. You can replace the stock 85 jet with a 90 or 95 jet, The stock jet is very lean to meet emissions, test & tune for your area/elevation. There were areas in the intake tube between the air box & carb that were necked down, I ground them out. I also used a hole saw to cut the plate inside of the air box to get more air to the filter. As for the CDI I left the stock one in. From what I've read some people have cut these newer boxes & never hit a wire/supposed to eliminate the rev limiter. I've also read the rev limit is higher in them than on the older models. I also cut the 5/8" pipe off the end of the muffler & welded a 1" pipe on. The biggest restriction was the 50cc's with the 72cc BB her bike pulls 28-30 mph up the biggest hills here in Marquette MI which leaves my friends stock Honda in a hurry