ITs a bit of a bastid, you need to knock the 4 little washers off behind it.
Best to jack the car up, undo the plastic nut and pull down the splash sheild bit, then with a bit of swearing you should be able to get a pair of pliers and take the washers off which will release the black plug.
I just hacked mine off cos i know i wont want it back on, you may wish to be more careful. take out the other side aswell or itll look wonky.
More cold air is better but i think its fine as ive said, the air that goes into the hole will be rammed up the pipe into the airbox, a performance element is the best plan for the airbox. think this is better than a IK certainly it worked for me, ive got a hill power kit on mine it sounds better but dont think it is as good as the original air box power wise, not in the summer anyway.
I think i had to cut away the black pipe so that it just sticks into the cavity so the air just goes strait up.
Its as good as any viper style induction kit i reckon, and isnt a few hundred quid.