The subject of uncomfortable drivers seat has been raised starting in 2009 when Ford started using "Soy" based foam. Why?...because they are saving millions in manufacturing cost not using so much oil to make the previous type foam. This is per Ford.
Now..I have a 2010 XLT with a drivers seat that I can't spend 20 minutes in with out it hurting. It feels like I am sitting on the open end of a 5 gallon bucket. Removing my billfold helped but I never had this problem in my 2003 XLT. I found out that the Dodge drivers seat was very comfortable and went out to find out the difference between the Ford and Dodge seats.
In my research I found an article about automobile foam seats and long story short the guy that wrote the article not only makes seats for different company's but does testing and works closely with the Ford Comfort Group. I didn't say he designs them, he test them and makes them per the car manufacture specs.
After reading my e-mail he went out and got a Dodge and Ford seat, tore them down to the frame, did measurements, cushion hardness test and displacement test of the foam and springs.
His findings are that the Dodge has stiffer suspension ( more supportive springs) as well as almost 30% thicker foam where your butt rest.( almost a full inch) Dodge ties their springs together with a brown paper covered ( to prevent squeaking) wire and crimps them to the existing springs across left to right looking at the top of the springs. This allows them to be more supportive. Ford does not do this allowing the springs to give more under weight. The Ford cushion is harder than the Dodge and is made that way because it is thinner.
I don't know how to post pictures but he sent me a picture of the Ford springs and marked where I should attach the additional support wires. It made a big difference on how much the seat sagged. That still leaves me with the thin hard Ford cushion. I currently have a piece of 1 1/2 inch thick #35 density super foam, 11 inches wide and 7 inches deep, laid between the springs and the bottom of the cushion, at the back,which has me almost where I want to be.
The other option as someone suggested would be to have a seat shop make a duplicate cushion of better foam OR ( and I'm thinking about this) buy a Dodge cushion, since I know how it feels, about $150 and have a seat shop fit it to the Ford Frame.
Sorry to be so long winded but I hope this helps. You can buy the support wire and crimps at an automotive upholstery shop and do that part yourself. If I knew how to post a picture of what he sent and how mine turned out I would. I am going around tomorrow to a couple of shops and visit with them about adapting the Dodge cushion, upholstery work required and cost. Good luck with your seats.
P.S. If you want to send me an e-mail, I will e-mail you back with the pictures and instructions he sent.
e-mail to firstname.lastname@example.org