Hold up. Manual trans mustangs comes with different mufflers than autos. Source? It seems odd that a company founded on interchangeable parts would do something so silly.
Well, they did. All you have to do is look at them. Stock, I can tell an auto just by the sight of the mufflers. The autos have a different, quieter sound than the more aggressive tone the manuals have as well. This is pretty well known.
So, after 3 months I'm bringing this back to say I don't know why but I'm getting slightly better mpg (went from 22-24 to 23-25) while it is only a bit more than 1 mpg that is an improvement of around 4%. Dan did yours change either with the Bassani or when you went back?