Few questions

[BoostedFC]

To make a 3 rotor version of the 16X you would need these.
1. extra housing
2. extra rotor
3. custom eccentric shaft for the extra rotor
4. another mid plate
5. engine balancing
6. lots of money

The 16X should be a promising motor, but if power is your goal stick with what has already been through R&D. Give it time for this new motor find a place, it isn't even out yet. The Furai is not your typical car & it's closer to the Le Mans cars so Mazda put a lot into it.

Titanium rotors would be too expensive, Mazda had already played around with Aluminum rotors & decided that they would be to expensive. The material is just one part of the equation. You still have the milling, balancing & someone willing to make them.