Modded an existing bracket and test fit a 1lb extinguisher in my car today with my after market seats. Will be confirming fitment tomorrow or thursday on an s13 with stock passenger seat. Assuming it should fit an s14 as well as the seats use the same mounting points.
I did notice that the bracket could have less of a bend on the mounting points and I will try to address this when theyre made due to the way nissan designed staggered mounting points. However, if this doesn't clear your seat set up (because theres a zillion combinations out there) the bracket can most certainly be bent downward toward the floor for clearance.