Needing some lower back support I have just realised that the centre back section of the seats can be eased forward and a sliver of foam inserted.
I had a spare offcut that was triangular in cross section thus when inserted gave me enhanced cushioning for the lower back.

Should have realised this before because I did exactly the same modification in my MX-5 which had a seat design almost the same as the Honda.

 

I have a Sparco lumber cushion that I use when in need, I find it's better than a permanent slice of foam since my wife doesn't need it.

 

How do you ease the centre back of the seats forward B? or is this on newer seats only?