Ok, you don't need 3", even 2.5" would be overkill. What you really need is a nice equal length header to help exploit the cams. Without building it for big boost or swapping in an S52, you're only going to get but so much power out of the M10. Honestly, there aren't any great places around here but this is where I'd go:

Oceana Muffler
1757 Virginia Beach Blvd # A
Virginia Beach, VA 23454
(757) 422-0944