There's a shop in Pacheco that uses a Mustang eddy current dyno. BRG Racing.
http://www.brgracing.com/dyno.html
I had my car there last summer for some work. They charged me $120/hour for tuning on the dyno. They now advertise $125/hr. It all starts to add up when you are tuning on a dyno because the motor has to cool a little between pulls or you get skewed results due to heat generation during a full pull. Usually 20 minutes with fans blowing helps cool the motor between pulls. I did all my own work on the tune up, although these guys will work on your car too at the same price.
Bill