Variable size people seats.

So I've got this Miata and I'm starting to like it. It needs seats. Those seats need to work with nice modern six point harnesses. Ideally they also need to work with the stock belts. Ideally ideally they also need to fit people of a wide variety of sizes from someone that would fit in a 14 inch seat to someone that would feel more comfortable in an 18 inch seat. 

The more bolstering a seat has the less it fits variable size people. This makes something like an Ultrashield not work so so great. So what are my options here? I need to get a bit lower. I need to fit me and my kid who is even skinnier than me. I need to fit friends who can't fit in a skinny seat. Help me out. 

Get the seat for the biggest driver and make inserts for everyone else.

In reply to JG Pasterjak :

That's an option. I do want to keep hooning this little beast around the neighborhood and doing store runs with it. 

This is my standard Miata recommendation 

https://www.corbeau-seats.com/product/le-pro/

I was able to order them directly from corbeau USA. They're a good compromise seat, especially if you're not 90% torso like me. There are mounts available that retain sliders or go to the floor. They are close in dimensions to Elise seats and use the same mounts, but accommodate harnesses. 

In reply to cmcgregor :

Dammit those are pretty. Seats would be worth more than the car which kind of sounds ok. 

Yeah. They're not cheap, but there aren't a whole lot of other seats like them. There are people that are perfectly happy dailying a car with fixed back race seats, but I learned that I am not one of them. 

My seats have a fairly thin foam/fabric covering the shell with foam inserts that velcro to the fabric in the typical locations (lumbar, thigh, bottom). Yuu could make a system like that work with different thickness inserts that anyone can switch in/out depending on what feels right.

I have Corbeau FX1 Pro seats.  They fit my 5'-9", 275 lb ass comfortably enough to drive an hour, they work with 6-points, and they have enough shoulder to keep even skinny guys in place.  And they tuck right into the Manic Miata:

I just sold my 18" ultrashield rally seats and they have good bolster support and aren't quite as intrusive as a full race seat.  Fit perfectly in a Miata. Can you use with both styles of belts.  Shoulder wings are great support feature

In reply to Ovid_and_Flem :

I just put my Ultrashield halo seat in on the floor. The halo actually sort of fits but the shoulder hits the door. Hard. Seating position on the floor is about perfect which does not help my seat hunt. 

In reply to Duke :

That is quite possibly the nicest roll bar pad I've ever seen.

I did a radical foamectomy to see how low I could get. 

Literally, bare seat pan with a towel on it. That's about the right height. I could go lower, but not higher. With a helmet I can just fit my hand between the hardtop and the helmet. 

So. If I want to keep the floor humps and the rails, where does that leave me? The part of the pan I'm sitting on is lower than the rails, so it would have to be a seat with a dip that fits between them. Is there anything other than the Le Pro that does that? I can chop the humps and mount sliders to the floor for a bit more room, and that would probably let me bottom mount an ultrashield. Probably? 

I left the humps, built a 3/16 steel frame, and bottom mounted a butlerbuilt aluminium seat in the challenge car. And i still think its at stock height.

I know you dont want to cut stuff up, but the spec miata guys have a dropped seat kit that seems promising. Or cutting the humps.

The logical button is cut humps, sliders on the floor, and an ultrashield. That should work out. The Le Pro is just so pretty.......

This guy makes one

Also fairly expensive, and much more aggressive bolsters so it's going to be a pain to get in and out of. I stopped taking my Miata on short drives and errands when I had to remove the steering wheel and wedge myself into it. 

Also - if you do decide to go for the LE-pro, make sure you do some research on mounts. They're diyable but there are only a few off the shelf options. 

Edit #2 - there's also Elise and exige seats. Exige has harness grommets. They're just hard to find