Why not do what RIO did and get an explorer intake? Its basically the same thing and can be found for a lot cheaper probably. But yes an intake will give you more HP but you wont see its full potential without a new set of heads... But you need to start somewhere
I wish I had my old wheels to give a true test of the difference, but I gained a few tenths in the 1/4 and that with going from 16x8 wheels and tires to 17x9s all the way around. The intake changed the motor's performance range quite a bit. I lost a little low end grunt, not good with an auto and stock stall... but I gained about 5-600 rpm up top.
Definately a good mod if you ask me. Once I get a real stall in her, she should really wake up.