Auto Edge (
http://www.auto-edge.com/) in Mahtomedi is a great shop, not cheap (I believe $140/hr) but regularly work/race on nice Porches and other euro imports. They are more of a euro shop (I suppose our Fiesta's are sorta euro) however have no hang-ups working on anything (my pops brings his mini, and Diesel Ram 3500 there for service as needed).
As a raceish shop they are also awesome for suspension setup for cars as well. They are also good with supplying your own parts.
Worth a call at least.
Another place that does have a shop but is a bit more limited on working with customer supplied parts is MAPerformance in Cottage Grove, MN. I'd call and see what work they do before planning on that one. they did have a shop Fiesta ST in the past and have developed mods for it themselves. They also had a small presence on the forum in years past.
I'd be interested in where you end up as well, so post who you ended up going to.