Thanks for the feedback folks. I did end up going to a muffler shop after weighing in on my options. Cost was a consideration as well as time to do the install if purchasing a kit myself.
I consulted a local shop that was familiar with buses, RV's and fleet vehicles. Since I prefer a single muffler exit I printed off a schematic of the banks system and they agreed to make a similar system. Its installed now and I'm pleased. Though, if I did it again I'd have the single outlet (past the muffler) run all the way to the back of the coach instead of exiting before the rear tire. Its a tiny bit loud while driving with the windows open.
Other than that, the piping is mild steel and the muffler is stainless. Done to a high standard, and my out the door cost was just a bit over 1k.
Muffer is a 30" fleet unit with dual 2.5" inlets to a 3.5" outlet.
Not quite a banks system (I'm still running factory exhaust manifolds as mine are in good shape without cracks) so I saw no need to change them out right now.
Thanks again for the feedback. I love the banks stuff, but I'm pleased with the current exhaust for about half the cost without the install time on my end.
I have a couple pictures and a short video of the new exhaust in my motorhome thread. Posts 64 through 70.