i used this product and in my opioin it sucks, my job came out the same way after test panels thinking i dialed in my gun, and tech. the finish came out patchy, tiger striped, and glossy in other areas. unless you have a vast number of years painting and a sata jet, i wouldnt recomend spraying this, i ended up haveing to sand and reclear glossy this time. came out like glass.
you could try like a med solids clear to get the flat look, or i think they also have a satin style depending on the paint your useing. once i even used a med solids clear and basicly just gave it many tack coats. or dry spray. since your not wet sanding it or buffing it. even if you did with the pre mixed it would no longer be flat. the job looked really good and consistant better than the product that your asking about. do some research before spraying. its a real pain in the butt. good luck if you get it to work let me know how you got it to lay down right.