If you get the C4 seats, make sure they are the "Sport Seats" and not the other ones they had. There is a huge difference in the way they feel, and I like the C4 seats alot better than the C5 seats since they will hug your body alot better, well for me anyway, and the hip cinch control(whatever it is called, it's what pushes in on the sides of your hips when you hit the button) is way better on the C4 seats. I am also alot thinner than alot of guys who drive these cars, so the C5 seats may suit the bigger driver's better. But if you got a 40" waste or smaller, get the C4 seats. I'm not a tailor, but I know what seats feel better.
Steve