6'3" here and while cramped it is such an enjoyable car there is no reason I would NOT own one. Other than I'm broke atm... But that Mazdaspeed MX-5 was sooo fun. Peeking over the windsheild to see exactly where the tires are hitting. Mmm mmm mmm. lol
Anyways, buy a nice aftermarket seat and get a slim low mount rail or mount it to the floor. An upgrade and you'll fit more comfortably.
From Miata.net:
What aftermarket seats fit the Miata without modification?
The Miata has a very narrow seat tunnel and should area. The key to fitting aftermarket seats is the width of the seat and the shoulders. The tunnel can support a 19.5" width and the shoulder area can support about just under 20". (YMMV, always measure.). Seats reported to fit are: Sparco Rev, Sparco Racing, Momo T-Frame, Corbeau ForzaI , Cobra Sebring, MazdaSpeed, OMP (?),
The problem with most aftermarket seats is they they are intended for racing and will not have the ability to recline. The deap seat well also makes it difficult to get in and out. Mazdaspeed sells a reclining seat but they are about $1300/pair.We have heard of someone using the 1st gen Integra seats with success. We personally like the Miata seat for daily driving - especially with the addtion of an aftermarket lumbar support or a towel stuffed behind the cushion.
Anybody got any that use existing holes?
Many manufacturers have generic brackets you can adapt.
Is it practical to put the seat in for events and then out again for daily use?
Yes, it is only 4 bolts to take the seat out.
Are they at all adjustable?
If they are adjustable then they are not race seats. True race seats are not allowed to have a recline function. The addition of the OEM sliders does give you some fore/aft movement but it is more limited then the factory adjustment since the seat are typically rigid at the thigh area.