ECU remaps, flashes, tunes, etc can squeeze more out of even the miata's NA 1.8L. You'll have to run premium gas. You may feel a bit more throttle response or it may be a placebo given the 5% gains like everyone else says here.
To maximize the output of the tune you'll have to do intake and header as well. On the NC miata the biggest restriction is that catted header.
Lots of advice here:
https://forum.miata.net/vb/forumdisplay.php?f=110