yes do yourself a favor and upgrade to the .18cv-rx, that's what I have... I love it! and for the spur and clutchbell, just get a racing clutchbell with the same amount of teeth as the stock one, or one or two teeth down/up. the spur you should probably just leave, it'll be fine... but as for your final gears, you're gonna need to swap them to the steel ones, due to the fact that the plastic ones are cheap and will break and grind and wear waaaay faster due to the mass power of the .18cv-rx compared to the T15....

the T-15 is a P.O.S hands down, you're better off with an o.s... very user friendly and holds a tune very well...