I had the 14" Maggy, it is a lot louder than stock and does drone (not sure if some folks know what drone is) on highway trips. Hence the reason for me pulling the trigger on a Maggy 22" The 22" is slightly louder than stock, almost (if any) drone at cruising speeds, yet you can hear it when you WOT.
I didn't really need the Mufflex system as I didn't feel like paying double for the unit that might not fit perfectly, plus they didn't have a 22" system.
Good luck with your purchase. Let us know how it works out for you.