A couple years ago i helped a friend swap 3.63s into his turbo nb miata. I didnt drive it and it broke down shortly after. Stayed broke down for a long time until this summer he had it towed to my house and i've gradually fixed a litany of issues and been driving and tuning it (adaptronic) lately.
Background on me personally, I've always disliked the high highway RPM/noise on miatae and that was one reason i traded off the NA i used to have and a reason why i've never thought seriously about using one as a DD. Where i live every commute involves either a lot of highway or in my case a lot of highway speeds regardless.
What's surprising to me about driving this car is that to me it feels like the gearing is STILL too short. I know the power level is a factor. I think some people would be hesitant to use these gears because they feel like they'd give up too much acceleration. That's obviously not a problem with this particular car because at 15psi i think it should trap 110-115mph in a 1/4 mile. But even out of boost, it has an acceptable amount of power in part throttle vacuum. It has a very acceptable amount of part throttle power at the 5-7psi it makes below 4000rpm. I honestly think it would still be decent with stock power levels.
In general i think anyone with a turbo miata who's hesitant to swap to 3.63s should definitely just do it. This car has great traction even with a lot of power (it barely spins 2nd at this power level on 225/45/15), great part throttle acceleration, and acceptable (to me) cruising rpms. This particular miata is one i could consider DD'ing, and that's high praise from someone who's not crazy about Miatas. Even on a non-boosted Miata, i'd probably still recommend it.
So, 3.63s in my opinion are a great mod and anyone on the fence about it should do it. And don't be surprised if you wish 3.30s existed afterward.
