If it's a DD, do a foamectomy. Then mount the seats to the floor. I haven't heard anyone who was happy with DDing a racing seat.

The other option to that is, dd with the stock seat and when you want to race, take out the 4 bolts and put in the race seat mounted to the floor.

6'7" have Ultrashield Pro Road Race custom fit in my NA, works great.

yea ill have the same issues

5'7", 220+ with very wide chest/shoulders and a big butt. 17" Kirkey Pro Street fits like a glove. I have yet to be in any non-custom seat other than the Kirkey that didn't hurt my shoulders or crush my ribs. Holds me plenty tight in hillclimb/TT events, and is by far the easiest to get in and out of. Much more rigid than the cheaper economy seats, too.

My biggest concern about seats are being able to fit the shoulder bolsters with the door closed. I see a lot of people recommending seats like the corbeau forza which is a nice seat. But will not fit in a normal miata without hitting the door. I had fx1 pros and though I loved those seats, I absolutely hated the fact I had no slider room and the door hit the seat.

The best seats for the NB are lotus seats. I freakin love mine but they are just becoming too uncomfortable for longer drives. They fit so nicely and look great. Just for DDing I'm growing tired of hearing my GF complain. And when other people ride in my car they don't anticipate how low the seats are and fall into them. I'm considering doing some ultrashields or kirkys, but I have a feeling it will be the same. I just have an itch to change to something else. But once these sell I really think I'm going to regret it.

Oh btw, I'm 5'7 and 200lbs. My fatass is comfy in most seats, even narrower ones.

If you get an aluminum seat with wings they can be tweaked with a big crescent wrench.