The AIH takes up about 20% of your intake area. I just took mine out a week ago and it's a big honker! I'd tell you that my truck feels more responsive but that's probably my mind playing tricks on me with my SOTP (Seat-Of-The-Pants) dyno.
I toyed with the idea of making my own "code killer" with a 470 ohm resistor but decided against it. I can easily get to the terminals if I need it. Most people say they don't ever get a soft code anyway (engine code that doesn't light up your check engine light). My service manual tells me that it doesn't come on until the outside temp is 0F and the oil is below a certain temp. Even then it only comes on for 30 minutes once per engine run cycle (each time the truck is started). Not worth the money to buy or the time to make (unless you live somewhere really, really cold).
I got my plug from Napa (I don't have the part number on me). It is an oil drain plug and comes with a rubber coated brass washer. It is 22x1.5mm and the center is the same size as the 3/8" ratchet without a socket on it (square inverted head). It was only $8 and change and fits perfectly. Torque that baby to 25 ft-lbs and you're good to go!
Hope this helps.