It wont be noticeable.
If you want one to improve reception slightly and don't care about having a full range (fire, ems, etc) scanner, buy one of these pre built or have someone build one for you.
http://www.ramseyelectronics.com/cgi-bin/commerce.exe?preadd=action&key=AR2Dedicated air band receive made FOR air band. You can't beat a receiver that's made only for the frequencies you're going to use.
Your receive is mostly the antenna. Get a better antenna, you get better reception.