Mr. Muffler was a very low-key, "We only do one thing" auto shop on Two Notch. As far as I could tell walking or driving past the place, they were never overwhelmed with work, but never wholly idle either.
"Mr. Muffler" himself was a cheerry 1950s looking cartoon guy who had a big smile as he carried a muffler. In the picture, you can see where he used to be, but the cut-out itself is gone. That makes me think that Mr. Muffler must be a chain with some other locations. Chains like to take all of their branding down from defunct locations while one-off stores don't really care.
This shop was located next to a sketchy trailer park, and all around the park are now signs warning that the park is closed and there is no tresspassing. One of those signs has been affixed to the Mr. Muffler store, making me wonder if a developer bought out the park & Mr. Muffler to mark this whole corner of Two Notch & Pinestraw for development.
UPDATE 30 Jan 09:
Here's the "Mr. Muffler" cartoon character from the Earl's Mr. Muffler on Sunset Boulevard in West Columbia. (Note that he is facing in the opposite direction from the one which was taken down from the Two Notch store building).
UPDATE 17 March 2010 -- I've added the full street address to the post title. Also, the building has been boarded up now:
UPDATE 11 January 2012 -- More pictures (27 August 2011) of the place boarded up:
UPDATE 30 September 2011 -- at some point someone has torn down the plywood window sheets. I'm thinking this was a break-in, or just random vandalism as they have now been put back up:
UPDATE 10 January 2012 -- As this picture from a few days later (1 October 2011) shows, the property owner has put up stakes around the parking lot to keep people from driving in there. I noticed 18-Wheelers in particular using the lot as an inpromptu pull-off: