Here is an update for all you power hungry. RK Sports of Murrieta, California has built custom made supercharger for your I4 and I5 engine. Easy 50 to 60 % gain. They also have custom hoods and body kit. Check it out. Links included.
http://www.valvoline.com/carcare/articleviewer.asp?pg=pht20050301rk&cccid=4&scccid= 6
https://www.rksport.com/main/home.asp

I couldn't find the supercharger on the rksport.com site, I only found brakes and exhaust as performance upgrades available on thier site. Is there a link that I missed? Where can I order one, and how much?

its on superchargersonline.com. but it would be easy just to go to yahoo and look it up as rk sport supercharger and its the second link down from the top.