Another "it's been awhile update." The Miata is finally up and running as of last month. I've been learning how to tune with the Hydra 2.5 EMS and I'm hoping to build custom seat rails within the next week or two. I need to run a compression test on it to see what numbers its achieving and then finally get it to a dyno once it's all tuned.
There was no definitive answer to this question but the two main problem child issues that were replaced were the water pump and the head was shaved 0.010" because is was slightly warped. I also installed the thermostat that Corky had removed and put the coolant reroute back to how it was without the T-Junction to the front water neck (which is now removed).
The headgasket was perfectly fine when we pulled it out. I think the overheating driving it home through Arizona mid-summer is what warped the head initially; this was most likely caused by the stacking of heat exchangers (intercooler, AC condenser, radiator) without any ducting which caused poor airflow to the radiator. The water pump may have been on its way out as well. *shrug* I don't know. The water flow looked fine when I blipped the throttle with the radiator cap pulled off.
Anyway, she's back to naturally aspirated but has the BP5A intake camshaft (from the Mazdaspeed Miata), valve seats on the head were cut and ports were flow matched by ART, and a header installed. I'll run it on the track for a season or two before deciding if I want to build my own turbo setup for the track. I want to get baseline water & oil temps at the track with the way she currently is and go from there. Temps haven't been too high here yet (barely braking mid-80's to 90 ambient) but water temp hasn't gotten above 205* F yet. I'm hoping to get the oil temp gauge installed in the near future.
The intake is only temporary until I can build a better solution. No way in hell I'm shelling out $200+ for a brand name or over $300 from BEGi. Ridiculous prices for marginal horsepower gains.