I've had a good read of Adams posts and your re-trim posts Lokiel.
I haven't found my seat too bad for daily duties and it's only seen one stint of 2hrs straight so far so time may reveal a different result. The foam in the base/back of mine is about 12-15mm thick as it sits at the moment. It is a series 1 non-probax.
I emailed back and fourth with Kemmler about the foam Adam used and for a half roll of the 1/4 inch foam it was going to work out to about $180aud give or take delivered to my door. I would prefer the 3/8 but that would have made it closer to $270aud delivered.
I couldn't swallow that pill.
My experiences with the Green/blue closed cell foam like you used for the inserts at the top of your padded section is that it collapses pretty readily in comparison to OEM when squashed under my large posterior.
I've just realised this step was missing from the seat saga. I pulled the Sparco for awhile as the cloth was rapidly wearing thin and reinstated the NB seat for daily duties. It now felt comically high and I found myself bracing when cornering the same way I did with the Sparco. So I cued the music and had at the NB seat with hammers and saws.
The result was I found the NB seat quite liveable with the bottom swab completely removed and very close to the carpet!


A trip to Clark Rubber got me some low density yellow for my butt and some medium/high density for thigh support. I went the bread knife/Utility knife route (because though I have a lot of tools a bench top voltage regulator is not one of them) and came up with this.
I shaped it a bit better and sewed up a black vinyl cover for it and it was put into service for a couple of months, being swapped with the Sparco when I wanted to really enjoy myself. I don't have a pic of it finished. Next time I'm in the parts hoard in the roof of the garage I'll snap one.


Long story short the green foam was showing signs of collapse. So unless I can find a local equivalent of the Kemmler Shock Tec foam I'm going to hold out and just recover the stock insert.
How did you go getting the UK mob to sort out the missing couple if inches in your inserts Lokiel? What foam did they use for the sections they made?