Loudest possible while still having a good sound and not popping without changing anything would be swapping current muffler for a flowmaster 10 series. Other options are carven or black widow something or other both of those brand make a loud/aggresive muffler. Both will be just a hair less noisy at WOT compared to a 10 series but trade off is they will both have a bit of a smoother tone to them. Depending on what kind of emission tests you have to pass, messing with cats can be a major PITA (I know from experience lol. ) Mufflers is like truck brands though, everyone claims the one they have is the best and have there own reasons why so be prepared to hear all 9f them, but I've played with all of the ones I listed along with magnaflows on hemis (rams and challengers) and to my ears what I said is true. But to each there own. I'd reccomend hitting YouTube and listening to as many videos of each one as you can to get a idea of the tones
Sent from my SAMSUNG-SM-G935A using Tapatalk