Need some advice

So here it goes: I have a chinese 139qmb motor (50cc 4 Stroke) in my scooter (please don't hate, I didn't know better at the time) and I would like to squeeze a bit more torque out of it. Everything is completely stock (besides removing the rev limiter). On the side note I've been thinking about replacing the carb with EFI system, any thoughts (useful links)? *EDIT: Forgot to mention that I live in Europe (Slovenia)