The only reason I posted in this thread is to state that no amount of money spent on modifications or faster cars will overcome a talent deficit.
The reality is if OP actually goes out and tries to measure up to others at an autocross or HPDE, nobody is going to make it fair for him. He'll be on track with other 'first timers' that have more prior experience and blow his doors off in a stock NA Miata, no matter what he does to his FRS. And odds are it will only happen more frequently as he moves out of novice groups into the big boy pool unless he puts some serious work in.
In what context? In terms of benchracing idealized test scenarios?
Who gives a shit?
I started going in depth, but then I decided I didn't care enough to finish it. The tl;dr is if you go back and look at the autocross results the STX FRS/BRZ's are about 0.2s slower than the F Street Camaro's and Mustangs, ballpark it's about $7k-$12k to build a competitive STX car but 90% of the performance is header, tune, wheels and tires, coilovers and alignment which can be done for about $6k. Add FI to that recipe and boom, your 86 is probably faster than a new Pony car at an autocross (or tight road course, modern autocrosses are big and sweeping to interest modern pony cars, corvettes, porsche's etc.) after about $10k invested into it.
To my knowledge the '16 Camaro SS has only been on Streets of Willow and landed a 1:22, current lap record in 86 cup in 'unlimited class' is 1:25
https://www.86cup.us/records/
I'd suspect similar minimum price of entry for that, somewhere between $10k-$15k to be 3s slower than a new Camaro. By looking up Laguna Seca stuff I think that will also be roughly in the same ballpark, ~3s slower than an SS. To 'beat' one on track, I think you're right, tens of thousands of dollars plus the skill and talent to put out a lap on par with professional racing drivers.
oh, then you did a very poor job of it.