Isn't the 190e an inline engine, with a single exhaust pipe? I'm just curious how an H pipe would work out.
If it's a split between 3 cylinders and the other 3, it might make a difference though...
I replaced the rusted out and scuffed euro dual exhaust on my SEC with straing pipe and what was supposed to be a relatively quiet muffler on in the rear.
Apparently I overdid the system size in trying to reduce back pressure while I was at it, as even with an H pipe in the system, ahead of the transmission, it definitely has a grumble at idle, roars when accelerating, and drones at highway speeds.
(Of course going from dual ~1 3/4" pipes to dual 2 1/2" pipes might have had something to do with it, not to mention the elimination of a set of resonators...)
A few of the sites that sell Magnaflow cats, as well as others have them rated by the displacement of engine that they are supposed to be rated for. Jeg's and Summit Racing come to mind right off the top of my head.
If you want to keep it free flowing as well as reasonably quiet, a fleet mechanic I know has recently started praising the Aero Turbine mufflers
here that he's tried on their fleet to replace the stock ones when damaged.
From what he was telling me, and then from what I heard in person, they do grumble a bit, but they have a reasonable tone. (and they'd likely be a 'bit' quieter if it weren't a 4" system, which was the one I heard, on a Suburban!)
Best of luck, whichever way you decide to go!