FAO those who have smoothed their airbox...

[Gareth F]

I just used pliers on the bottom section, as soon as you started to bend the plastic it snapped off flush  

Also fitted 76mm air intake duct which you cant really see  

[nige_s]

didn't bother on mine really i can't see it making a vast difference,although i did remove the resonator trumpet on mine 

anyone know what the trumpet does? At a guess makes it quieter?

i think as Rich says it does make it quieter to but also acts as a smoother so to speak to funnel the air smoothly into the opening of the maf  
[/quote]

Yes, smooths and straightens the airflow a bit like stacks/trumpets do on carbs, also helps the torque a little.  Though the difference is probably not noticeable in day to day driving.