Thought I'd add a couple pieces of info to this thread.
To remove the clips from the seat back, I pulled the 6 seat bolts (14mm), lifted the seat off the hooks, folded flat, then removed each clip/hook with a Torx T-30 on a tight clearance ratchet.
Once I had the clip/hook off, I clamped them in a vise, removed 2.5cm (25mm/0.984in) with a hack saw, keeping close to the factory angle.
Everything works perfect, once locked in, nothing is loose or rattles, and the hooks grab plenty of material. What a great modification. Now, off to the fabric store to finish the back of the seat.
