I'm 37 going on 16 and have had the experience you are looking for just last week. To get the loudest thing on the road you are half way home with the headers you have already. As Grigg says "no mufflers", just straight pipes, 2". I ran duals back to the headboard then brought them together into a 2-1/2" pipe. Then ran that into a 4" stack. The stack is important because, 1) it amplifies the sound, and 2) it gets the sound up off the ground a ways so that ALL can hear. And trust me they will hear you way before they see you.
I got away with it for about 2 months and this is what the cop told me last week when he pulled me over: "That is the LOUDEST thing I have ever heard." I didn't argue.
So to tone it down a bit I put two glass packs on it. It's much quieter, but still has a nice little rap. Have fun.
