I am not that short or tall,( only5'7"), but I have experienced all of this. I replaced the Pirelli webbing only to have it fatigued again, used 1/2" piece of plywood as per dimensions published in "Rolling Magazine" many many years ago, raised the seat to it's highest position, but non seemed to be the proper solutions. Finally this past Winter I replaced the webbing with the seat belt webbing sold by IPD, (http://www.ipdusa.com/products/6185/103552-seat-web) and had the bottom seat cushion rebuild using new Volvo seat padding foam p/n691612. What a difference this made. It is so comfortable now and I sit so much higher that I had to lower the seats and my wife thinks that we now have a new car or old car with a new suspension system.