I am in Spokane as well and I am interested in your views on the 600 Alpha One. It's a 154 x 3" x 3.5" pitch and I am thinking for our area it might just be a great sled. Please send me a PM with your personal thoughts because I may end up trying to find one as well.
Yes be careful putting a can on the 600... they are LOUD. I put an SSI stainless on mine, which I don't think are super loud on the 800, and it was just insane. Switched to a Bikeman Full Velocity and that was still extremely loud for the size of the can.
I don't think there will really be any aftermarket "quiet" cans that will be worth it, I bought the mbrp Trail can and in my opinion it's still too loud, I'd almost go back to stock muffler if it wasn't for weight savings and I may still choose to regardless. It's still half way between stock and a straight pipe/Race muffler though but it's loud enough to be annoying lol