it depends on a few things about the car. what engine size is it? and what do you plan to do to it as power wise? i go an Enthuza exhuast from another miata owner here and i like it alot. sounds real nice and is not too loud. there are several companies out there you might wanna check out. the most common ones for miatas are RacingBeat and Roadster sport. there are some other not so common companies that make exhuast for the miata like Buddy Club, RS*R and a few others from the JDM. most of these exhuast usually cost quite a bit. good thing is you can some times find them used....or you can go the cheapest way and make a straight pipe lol but that will be loud as hell. if you want remind me next time you see me, becuase i might have something for you.