Think i follow your question??

Dont have any pics to hand as kept mine out of sight - to look more original. (standard rs500 top of box) I ran a 3/4 inch drill up and down the front face of the lower section of the airbox (in a series of holes) and opened up the side where the square section normally connects to the inlet pipe. Seemd to increase airflow quite a bit and I even had my pipercross air filter get sucked out of its mountings and into my turbo intake pipe. Luckily it didn't reach the turbo itself!

K n N jobbie in there now so problem solved.

On a T4 I got around 450 bhp without any difficulty using this technique to let the air in

Just seen KSAs post - maybe I misunderstood the question