What software are you planning on using to tune the Mustang with? You should definitely conduct all pre and post mod pulls on the same dyno that you are going to be tuned on. In my opinion, the best facility to actually dyno tune on in Portland is Rrev. They have a Dynojet with resistance capability, so you should be set in that respect. Tim and the other guys are experienced in the Dynojet software, so they should be able to load the correct test conditions each time you come in.
In terms of one tuner over the other, I will say that with the available SCT and Diablo software, it will be easy to get you a tune with a safe A/F ratio across the powerband. Will you get maximum safe horsepower and torque tuning the way many of the local tuners tune? No. Will you get a decent, safe tune from any of the local Ford-specific tuners? Yes. That being said, call AFP or KKP for a tuning quote.
If you know how to use a Mustang Dyno, it can be a great tool. As Allen said, it is easy for a novice or dishonest tuner to manipulate variables in the software and skew the results. If you are on top of things with your dyno sheet, you should be able to detect this. Most dynos offer an opportunity to screw things up if you tune with different test conditions and input information. As a consumer and car enthusiast, it is your job to monitor the dyno operator as he/she is inputing this information to make sure that things are accurate.
Have fun and good luck!
-----Bart
