Nope, sorry man..
18" Resonator - Low growl, low drone - can hear it just fine outside!
12" resonator - some drone, louder outside.
No resonator - definite drone between 2-3.5k rpm, quite loud outside.
That's pretttty much it in a nutshell!
And by the way..the 18" resonated is
definitely louder than stock. Mild when cruising, mean when you put your foot in it!