SCT with custom tunes -- she can go from mild to wild. All her choice on which tunes she gets. Don't go to any race or crazy tunes until she has that thing studded!
Exhaust - pretty much any exhaust like MBRP, Silverline, etc. will do. I think you can get a 4" downpipe in a 6.0L, but sometimes it requires some "modification" of the firewall.... otherwise, 3.5" DP to a 4" or 5" exhaust would do her wonders.. and straight pipe that sucker! 6.0L sound bad a$$!!
Just curious... but why wouldn't you go ahead and buy an SCT that CAN be customized in the future, even though you may not need custom tunes now, and just run some canned tunes or a "weak/safe" tune instead of buying a Superchips tuner now, then realizing you are stuck with that when you want to upgrade and now have to sell it and buy the SCT/other tuner???