You can expect 15 horsepower if you had a small child or kitten stuck in your airbox.......but other wise, no. Over stock you get about 5-7, almost in the range as the infamous pullies that everyone loves. Get a k&n cone, and then rip out your airbox. Look at how stuff needs to be routed, then go to Home Depot and look at all the lovely PVC piping in the plumbing department. If you don't like the white look, you can get ABS piping thats next to all the PVC stuff, simmilar, just black the ABS is. If you have an unnatural fascination with PVC piping, like myself, you will eventually understand its powers and make new things:
http://www.goldmann.com/spudgun.html