Hi Frank,
Using KIR-47900 Seat, Aluminum, Intermediate Road Race, 15 Degree Layback, 18 in. Hip Width,
I added a custom bend to the back of the kirkey seat. It is 5.5" from firewall at bottom. 2.5" at the 10" high bar and touching the 24" square bar and touching the angled roll bar.
The cross brace is right under my bent knee. So no problem at all.
Here is a picture of my seat test a long time ago. I will be permanently installing it this week. I'll post more pictures.
Bob
seat.jpg