2000 Runner 180 tuning setup advice, help!

Hi all recently purchased a runner 180 due do loss of my left foot during an accident last year where i came off my Gsxr1300 (busa) wanted a scooter with a bit of poke and the runner is great in regards to tuning i have brought a malossi mhr exhaust (have been told they were the best? polini kevlar belt (better acceleration? polini clutch (standard was on last legs, my question is what weight rollers should i use in my standard variator and do i need to a uprated contrast spring also with the polini clutch and the springs that come in it ok for the setup i will be running? Also is it worth while getting one of these polini or malossi air filters noticed they do a normal and a double foam one whats the difference and which one is better? Any advice would be great, cheers L