Well, they offer two Loudmouths. Loudmouth 1 has no muffler. Loudmouth 2 (renamed Power Flow) has mufflers. They used to call them both Loudmouths untill recently.
It's not that the emmissions are so bad, it's the noise level. Most communities have noise polution laws.
Loudmouth 1 is not a muffler, it is called a resonator, it has the cylinder like look of a glasspack, but nothing on the inside..Loudmouth 2 essentially is a glasspack, it has fiberglass (or ceramic??) packing on the inside of it.. the POWERFLOW is a third muffler made by SLP that is the traditional muffler square look, and is the quietest of the three.
However, ALL THREE are emissions legal, as long as run with catted mid pipes, you will very rarely get pulled over for noise pollution with just a catback, even SLP, unless you pass a cop at like 5k rpm, but you'd be speeding then and it's a whole different story then..just wanted to give you the right information on all of that
oh, my vote is SLP