not too sure about the 07 model, but for up to 06 model, you need to cut a 'bridge' inside the CDI unit. This bridge was put in place so that the bike can pass euro 2 emission regulation and can be produced. But I also informed that the newer model CDI unit does not have this bridge, so to cut off the limiter you will need it reprogrammed.

As for making it fully unrestricted you will need the 'RAVE' unit which is exhaust valve system. I'm not too sure how much a RAVE kit cost, but you will need the RAVE control unit, RAVE valve and the solenoid. The system opens up the valve when the engine reaches 7000 rpm. You can tell that the system works by feeling a slight jerk when it goes above 7000rpm, oh and it sounds a bit different too

Also if you take a look at the airbox snorkel, one of the holes should be blocked on your bike, you need to cut this open and then install a bigger jet to compensate for more air intake.

To add a bit more you can have a look at aftermarket exhaust, the stock exhaust is pretty good so most people only get around 3-5hp gain from it.. so its up to you

With my unrestricted RS125 I get around 23-25km/L or just a bit under 5L/100km.