Identification Help Please......

I recently picked up a 2001 Gt and as im going over the car i am finding a few things that lead me to believe the car has been supercharged at one point or another, but what i have come across i cant figure out why it may have been done. On the rightside of the plenum on the side the previous owner drilled and tapped a fitting which could have possibly been for a boost guage? or not.. who knows. The issue i have now is that they put in some sort of fitting that is still alowing air to be pulled in. If i place my finger over it you can hear and feel quite a bit of air being sucked in. If i press hard enough to seal it off the car stalls. Why would this number one be there and number two why would it stall the car out once its plugged up.. I had plans on going and getting a plug to screw into this , but upon stalling out the car with my finger over it< im assuming it wont run with it plugged. Please see the pic so you can get a better idea of what im talkin about... As far as i know the car has port and polished pi heads, stage 1 comp cams , Underdrive pulleys with carnk pulley changed. Thank you in advance for your time and help in this matter... What do you think i should do.? The car seems to smooth out when the leak stops but once its totally sealed off it stalls.

Please look at the gold fitting

I though that as well but nos nozzles are usually around 1/2 inch hole. this is a 1/8 inch tops. Also a nos nozzle at that angle would also be working against airflow. I guess i really dont care what the reason for this hole is , im more concerned with the fact that it shouldnt be there and when it is plugged up the car stalls. I can imagine that its effecting air fuel ratio and what not because its all after the sensors. I gotta say im at a total loss on this one.

Unfortunately no, my friend has the same car no fitting... Searched through many pics and forums and no one has it...