The only real issue I ever had with S-Line seats (and I really like the nappa) was the seat base tilt angle when new.
For me at least, the most comfortable position is found by;
setting the seat height to its lowest position first (I prefer to feel like I'm in the car and not sitting on it)
then drop the front of the seat base so I don't feel like my **** is dropping into the base/backrest joint
then adjust the distance from the pedals
then the backrest angle
then the steering wheel distance (I have this as close as possible because driving with almost straight arms is uncomfortable after a while)
then the steering wheel tilt so the top of the wheel is below the top of the instrument brinicle
then fine tune the above and sort the lumbar.
I've never adjusted the back of the thigh extender.
To me at least, the tilt angle of the seat base is the most important adjustment for comfort.
Despite putting my back out and feeling like a cripple for a few days, I was more than happy doing a 6 hour plus drive to Newcastle the other week, with just one quick stop for a coffee on the way.
Whether any of this helps or not, who knows.
