My BFI intake is a compromise between stock and the real BFI. I dont know the real world gain but i can really feel the difference. and its not obnoxously loud.

I took the stock box and left the part for the stock Cold air feed in tact.
Right above it I cut out an oval area slightly larger than the oval hole for the stock scoop.

when i put it back in the stock scoop is attatched so it can get cold air from outside, and the other part can take air in from the engine bay under punching situations.

basically off the line it is sucking up the air mostly from the engine bay when it really needs alot of flow, and when above or close to WOT, the atmospheric pressure drops to 0 psi in your intake system and it will equally draw air from the cold scoop and the big hole.

I dont think this is better than making the original BFI where you seal up the headlight and everything, but its a good compromise for someone who doesnt want to go through all that hassle.

Honestly all i wanted was to get rid of that restrictive bogging down i get right after i drop the clutch hard, and now its completely gone and up top it pulls even hard and i know its getting some cold air cause the scopp really only works well when the car is moving anyways.

I hope that made some sense. i can post pics when i get home.

 

heres a pic, K&N filter oiled and dried very carefully.

its not the best cause it sucks up some warm air and cold air, but its better than not getting enough air. engine revs much better now.