DRT 33 Tooth Long 4th Gear
Even with a Malossi 24/63 upgear, the current peak power (32hp) is at ~86mph (7500rpm) fading out (21hp) at around ~95mph (8500rpm). With no juice at all by 100mph (just under 9000rpm).
With a longer 4th gear this will locate peak power @ ~91mph, fading out at around 103mph.
http://www.drtdenis.com/catalogo/sottocat.htm%20DBE?idcat=151&catee=02
I have calculated I need ~25hp (rear wheel hp) to do 100mph. So the upgear kit may just get me there :)