The mixing instructions for the flattening agent will give specific amounts to add for the amount of gloss to be achieved i.e. flat satin , semi-gloss , etc . I had mine sprayed black and satin clear and it looks great . Good Luck !!
The amount of flattening agent is the question. There are many degrees of gloss, semi-gloss, or matte finishes. That's why I want the paint code from Ford so there is no question.
Your car is very nice looking. I love the blue with silver stripes. I was torn between the Grabber Blue, Gotta-Have-It-Green, and the Sterling Gray. I chose the green since it's my favorite color and I have 2 other projects slated to be painted in Grabber Blue. The dark gray was awesome but just too typical for me. I also tend to like the loud colors that scream to look at the car; I mean it is a Mustang after all.