alot people like IPS in columbus http://www.ipsmotorsports.net/
I didn't see anything about Mazdas on their page, though.
I know it's not their specialty but I think they do have an awd dyno. There's just not alot of mazdas around to get tuned, they were going to do my MSP w/ a Haltech. One of the only places to respond back to me when I was looking.