Reinharts have a nice sound, also V&H ovals that are a bit louder.
A stage 1 added to the pipes will work well but you would need some additional fuel with this combination. I like the TFI because it is a simple addition and works well. No computer needed for setup with it either. I run it on my bike.
I run the Techlusion TFI on my '03 RKC, but my vote is for the Hooker Tuned Flows. They have a really nice growl when your "being good" with the right hand, but a loud bark when you twist it hard!