First I removed the torn diaphragm. I also removed the two aluminium pieces at the sides so I could add more holes.
I had to temporarily un-thread the left hand front-to-back so allow me to get enough grip to stretch the side-to-side ones.
All done. The three middle side-to-side hooks are 30mm and are from the first seat diaphragm I bought - there is no reason I used them other than convenience. The Vogue originals and the ones I made were 20mm - you can see the difference.
The strange interleaving is because to front and rearmost straps would have been damaged by the webbing clamps if I had run the side-to-side trap across the bottom.
Cost of the Premium Webbing plus clamps for the base was $26 - with postage from (www.diyupholsterysupplies.com.au/home/) This includes enough for the passenger seat when it inevitably fails. The webbing is also heaps easier to put on and really easy to "get it right". My advise - don't bother with the diaphragm approach at all.
If this was being done while the seat was completely disassembled then you also would not need the aluminium pieces - just drill extra holes in the actual seat frame. Another time saver over what I did originally. The 0.8 stretch was about right for the base - I wouldn't change it.
I will post how it holds up over time but I really don't expect any problems at all as two or three straps can hold my 80kg weight easily - and there are eight.