Used Beatrush PPF brace for the NA8 Miata. If you have a NA6 you have to add the tabs for this to work or have the rear subframe from a NA8. These are $142 new, selling for $100(about 30% cheaper than new) given the cosmetic patina ;) plus shipping in the US only. Will also trade for a NB version. Contact via PM or email phatchevelle@hotmail.com.
In case you are unaware of what the brace does here is a description:
The Beatrush Miata PPF Performance Bar restrains the Miata drivetrain to enhance rigidity, which makes the suspension movement more precise and enhances steering response as well as traction (significantly reduces wheel hop). Light Weight, Strong, and Rigid. Made of Aluminum. Developed by Beatrush of Japan. Track tested for functionality by Beatrush.
Also you will be able to hear some gear whine with it, IMO, it is barely noticeable but everyone's senses are not as sensitive as others.