find an expansion chamber, get a new belt (i use the dayco #17415. not the best but it works), upjet and you'll notice a huge difference. just the expansion chamber alone gave me about 7mh on the top end. dont forget to upjet, i soft seized my PA50II after throwing my expansion chamber on in about five minutes. no joke.
if you want to get crazy, mod your variator i'm doing that right now. just took a little break to smoke and search the interweb.