You might just be my absolute hero!
I would absolutely kill for 1 or 2 inches of additional headroom for helmet clearance! This seems to be the ticket!!
Questions:
1. I'm not sure I understand what you're saying about the seat belt buckle mounting and I can't tell from the pictures. Did you have to do any custom fab work to get the buckle mounted?
2. Other than the Sparco seat mounts, do I need anything else?
3. Do the Sparco mounts have to be modified for this to work?
4. Why do you think this doesn't look factory?
I have a 135i, but I assume the seat mounts are essentially the same.