yah yah, i heard someone calling my name? hehe aprilia si bo?
hehehe, aiyah, aprilia u wanna mod ah? But u must prepare for
somethings lor...
1) Eat petrol like FUCK!! Full tank tahan 1 day, 2 days at
most...
2) Must tahan to siam TP (if u going for pipe)
3) Got $$.
So mod is standard one lah. Basics are
1) Fuel Jet
2) Reed Valve
3) Sprockets
4) Pipe (Arrow, RS, chamber)
5) Settings
6) drill some holes on your air filter to maximise a little air
intake for better pickup.
If u still have $$,
7) Change to Mikuni carbuerator
Change to single ring piston
9) Port your block
10) Splitfire cables and plugs
If u still have $$$$$ dono where to spent,
10) change to carbon fibre fairings/rims.
11) customise your frame by cutting off thos "extra" metal parts,
drill holes on your swing arm
12) Change to hydrolic suspensions.
13) Take out meter/lights.
14) Put racing damper.
15) Use steel brake hose for better braking, (ur bike so fast must
use better brakings)
16) One seater
17) Maybe get a Pilot Race slick tyres.
1 I think the radiator oso can modify. (4get how
liao)
Recommended to pump jet fuel if u have $$, in SG i think Shell XO
can liao. 2T can use Castrol A747 premix and Motul 800 premix.
Engine oil for aprilia recommended Rock Oil GRO geor oil. SO far
only these stuffs i know... 
But last advice is... don mod lah, no point. Not racer, mod for
what? hahaha original original can tong pang gals can liao..