Pierce Motorsports also makes a chassis brace for our cars, no idea what the quality is on them but they do have them in stock.
Are you still on the stock radiator? I replaced mine with a Mountune because I was constantly going into limp mode after doing full cobb stage 3 + stratified tune.
Also have you thought about trying to purchase a set of Recaros second hand? I hated them at first but once they break in to your body shape they are amazing. Best OEM seats I have ever owned.
The mountune brace is perfect. No need for anything else really. That with a TB traction bar has been great so far.
Stock radiator. Never had an issue on track, autocross, long trips, short trips, dogging it....etc. Car runs flawlessly and oil temps stick around 220*F and coolant temp is 198*F across the board. No clue why mine has been good but others have that many issues.
I tried to find Recaros multiple times. Just too costly for crap that people want to throw around saying they are "mint" when they arent. Also, due to the style of the Recaro its not very comfortable for me(5'11" 250ish lbs). Instead of spending north of $1000 i just had a reupholster company re-bolster my stock seats using Recaro dimensions(see photos above of added bolstering) but with better foam and using fabric padding instead of the plastic that Recaro uses inside the seat covers. Mine are wider at my thighs than the Recaros and a bit taller at the very end of the thigh bolster. A friend who has the Miata in a few posts above(silver NA Miata) sat in the newly bolstered seat and he had room to spare as he is also 50lbs lighter than me. I had to go sit in the seat as they were shaping it to fit my body.
So id love to have Recaro on my headrest but now my seat is custom bolstered for my body, with Recaro levels of grip and without having to worry about keeping them clean or wearing them out. 10/10 would do it again and will do it again here shortly on my passenger front seat so they match.