We just finished installing a Procharger and custom tuning our first SRT Challenger. With 6lbs of boost on a completely stock Chally, with a our custom tune the car made 513 rwhp. Here is a link to pics of the kit, the install and the dyno graph. http://www.dtpracing.com/component/option,com_gallery2/Itemid,91/?g2_itemId=17325 Let us know what you think.
Once we saw the power gained from "custom" tuning and 6 psi, its hard to suggest any other mod for the money.