49cc Derestirction and Air Filter

Hello,
Ive recently put a new CDI in my 49cc SYM symply scooter, it raised my top speed by about 4-5mph which I still do not find fast enough. I have new 6g rollers and am currently working on derestricring my variator.

I would also like to gather any information on changing up my air filter to a performance one. My question is that I'm not sure how the air/fuel balance is decided, I know that if it was too uneven then the bikes engline will go lean but I was wondering if someone could inform me on how I would measure the amounts of each in order to get the perfect mixture.
Thanks

 

Please don't be fooled with "performance" air filters on small cc scooters, the std air filter/box works great. Actually someone spent a few minutes designing the air filter to flow exactly the right amount of air for any throttle opening!
What SYM is it, 2t. 4t?

 

It's a 4 stroke, and I'm just going off what I've seen online about increasing the speed of my scooter and do not know a lot about performance enhancers etc.