Mike,
I did this on my 94 RT (check the archieve to view my dyno sheets). Basically, 352 RWHP bone stock and 390 RWHP with K&N's, smoothies, and removal of the mufflers (located rear of the cat in the side sill, just under where you enter the car). An added benefit is a MUCH COOLER side sill. Difference was very dramatic!!
I have since then added a borla cat-back due to some droning and the sound of straight pipes. No dyno on this yet!! Let me know if I can help.