That was my main thought Robin, is would the filter allow for a better combustion and therefore more efficiency from the engine, car is fast enough for legal driving but there is something intriguing about making the car as good as it can be in OEM spec.
....*cough* It's a fine line though. Is swopping to another VAG part still oem? TT wishbones, R32/S3 brakes, etc for example.
It's also a seductive introduction to that slippery slope of modding.