Please see my write-up, which I completed many years ago, here:
http://www.zcarcreations.com/howto/corbeauseat.htm
In short, I got rid of those seats. I could have spend countless more hours trying to shave a few inches from the mounting mechanism but would have ended up with a less annoying version of the same problem.
The next iteration for me was to get new foam for the stock seats. I had the same problem: headroom.
I've been out of heavy duty Z work for quite a while and into raising kids but my Z now has some good old worn out stockers to sit in. Headroom issue solved.
I now know that the only way to solve my issues, at 6'3", is to do some serious work on the mounting points and floor pan.
Craig
