Just get AP1 with few quick mods later and call it a day.
My brother has a AP1 and yes you are right a few mods and its fast! I don't like the feel of that car. Very light steering and feels like a the steering wheel is attached with bungies. Haha!
I spoke with Mike, aka "psychoazn" on the forums who owns a S2000CR and runs a shop with a BR-Z. The dude is fast, like sub 1:24 at SOW and 2:01 at Buttonwillow 13. Anyway, last time I was at Chuckwalla I had him instruct me & show me some of the secrets to help me get in the sub-2:10s at Chuckwalla.
Anyway, after the lessons I asked him specifically which car he thinks is a better one between the S2000 and BR-Z. He basically said if you keep it stock, the S2000 since it's faster out of the box with better tires. With light mods to moderate-high mods, the BR-Z/FR-S takes the cake because in his words "it's simply a more balanced chassis." For full race (as in with aero) it's a toss up as both cars have their strength's and weaknesses and the possibilities are pretty much endless. The S2000 has aerodynamic lift issues and needs a wing to keep the rear down. The BR-Z/FR-S is a zero-lift car from the beginning but benefits from more frontal downforce (this is hard with the weakish front bumper).
Anyway, I wouldn't rule out the BR-Z/FR-S, because it's definitely getting quite a following in aftermarket tuners. In fact almost all the track events I've been to as of late, all the S2000s have left and been replaced with BR-Z/FR-Ss.
But if you want a surefire track car, a bargin price, huge race following, & a HUGE parts bin, I don't think you can come close to the Miata. It's also a great car to hone in your driving skills because the limited power requires you to take the best lines to get the best lap times.
All that being said, I want my next track car to be a C6 Z06 Vette. :biggrin: