How do iturn up the volume???

[GoodtobetheKing]

I really like the tone and depth of my new slip-ons, but I'm looking to make my V&H HI Output Slip-Ons louder on my 2012 Road King. Certinaly, better performance is also an added bonus. Any assistance is greatly appreciated!

Here's my set up:
Stock header
Stage 1 Screaming Eagle air cleaner
Fuel PAC tuner
The engine is entirely stock.

I'm considering adding the V&H power duals power chamber or true dual headers. Althought these additions are exactly what I'd call a cheap date, I'm pretty motivated to turn the volume UP on the exhaust. I'd like to do this in the most cost sensitive manner possible.

Thoughts???