I dis-stink-ly 'member way back when the MX5 came out, that they used the tranny from the 929 because it was the stronger of the rwd pattern 5spds they had, the other being the one in the p/u for the small 4 and the 2600i. May have changed with the 1800.
I'll have to take your word on that, because the only thing I distinctly remember when the Miatas came out was that I was in 7th grade. <img src="/forums/images/graemlins/lol.gif" alt="" /> It's interesting that I haven't yet read anything about that on the interwebs, will have to look it up sometime. As Reuben mentioned, the 5-spds were all the same on the 1.6 and 1.8, and the power adding folks have found out they're good to about 250 whp. The newer 6 speeds will bolt right up, and are much stronger. However, the gearing is such that 6th on a 6-spd is really no taller than 5th on a 5-speed. Some guys with powerful motors and a 6-spd have regeared to 3.63s, both to have a tall highway gear and to reacquire a usable 1st gear.
Don't see too many rotary swaps into Miatas, but it has been done. I think it requires some work to the firewall and subframe to mount it up. I like rotaries. Or rather, I like driving them when I have the opportunity, but I'm not sure I'd want to deal with apex seals as often as they are necessary on track cars. <img src="/forums/images/graemlins/smile.gif" alt="" />
If you're after stupid power, Flyin Miata has a new tube subframe designed for swapping in an LSx, with a T56 tranny and a Caddy CTS diff. I suppose it would make for a fun street car. <img src="/forums/images/graemlins/evil.gif" alt="" /> <img src="/forums/images/graemlins/lol.gif" alt="" />
