I've used Amsoil GL-4 in the trans for the past few years at the track with good results. However, without any sort of additional cooling going to a shorter change interval is going to be much more important than the fluid you use (assuming any modern synthetic). Last year I would change mine every 3 events, but I think I'm going to have to go down to after every 2 events.

 

Oh ok thanks for the advice!

And I just ordered some AMSOIL

 

For track use, use a good 90 weight like the Redline MT90 or the Amsoil - maybe even try that Ford stuff the Miata guys rave about. Replace annually. The MTL is OK for street use but does not hold up as well to the heat from track use.

I tried the NEO but I preferred the smoother shifting provided by the Redline and Amsoil when hot. Smoother in my trans. YMMV.