HI,
I have similar problem with lumbar pain shooting sometimes mostly to my right leg and your post brought a faith in resolving this issue successfully. I have just opened my seat back and started to stuff it with memory foam (bought few pieces of different type, toughness, flexibility etc.. Could you please send a picture how you did this, I mean how much of the foam you stuffed in certain places and what was its toughness, uphoslsterers use differnt types which vary mostly with tougness of foam. Did you struggled with the vent mounted in the back ? Did you remove this for the time of adjusting things in ? I would apprciate any details you can share.
Thank you
Adam