I was down at my local Porsche tuner shop checking out the latest builds when I came across a tech modifying the reverse gate on a Porsche GT3. They pulled the reverse detente spring and stretched it out. They then installed it back and placed a ball bearing between the cap and spring for additional spring pressure. The changes resulted in a much stronger pressure required to get into the reverse gate. The car's owner complained when going 4th to 5th he would inadvertently go into the gate for reverse. The mod seemed to cure that.

I can't help but thinking the same could be applied to the Miata Six speed. If you could find a way to make the reverse and 1-2 gates stronger you could drive the gear box like a 4 speed H pattern on track more. Having more spring pressure on those gates would allow you to ride along the edges without slipping into the gate. Should inspire more confidence on track!

 

 

this may not be exactly what you are looking for but it does offer some information.

https://www.miata.net/garage/stuckreverse.html