Performance air filter for scooter?

My scooter’s running fine – no real problems. Nice and zippy in town and if I don’t overload the engine it doesn’t overheat. Only thing is it doesn’t quite rev freely through the range. Feels like not enough air is going through. When Redwagon tried it he suggested poking some holes in the airbox somehow – he gave a very detailed explanation though I ashamed to say I’ve forgotten it. Anyway, I thought that as a preliminary step to see whether increasing air flow would help, I could install a “performance” air filter – one that’s less restrictive.

Any thoughts? What brands are available here? The bikes a 100-ish CC 2-stroke with a stock exhaust pipe.