Assuming this is for your NC Miata, the most common thing to do these days is remote tuning. Supposedly, the NC Miata's Denso ECU is quite trick to decode, so I'd personally feel better with tuning shops that specifically focus on the NC, as opposed to local tuning shops that are not NC-specific.
Comments
2014 Mustang GT in F Street
1999 BMW 323i for Rallycross
2011 FSP Canadian National Champion
2017 FS Canadian National Champion