How much power can a stock 1.8 rear end take (repeatedly)?

Far more then the stock motor. Generally its the axles that break, and its if you get lots of wheel hop.

So, I've decided to do things a bit differently. I think I'll just keep the NB2 (2001) that I have and invest in a decent paintjob and hardtop. Not much point in selling a Miata to buy another one. My biggest issue is that the exterior paint doesn't match the original paint, and the engine bay / trunk are still the original color. But whatever. I'll just re-do the exterior paint and I can keep on having a black and green Miata.

So this changes things, at least a little bit. Current questions are: What ECU to use? As far as I can tell, Megasquirts for the NB2 are significantly more expensive. Not a huge deal, but if there's an $800 option as opposed to the $1200 PNP Pro. Also, do I actually need the VVT tuner, or will the MS handle that?

Anything else that will change in working on an NB2?

Thanks as always

MS3 can control vvt. MS2 will require vvt tuner. I'm pretty sure I just saw a used ms2 pnp on one of the classifieds for like 4-500 (Edit: $400 shipped here). Add vvt tuner and you're good. Megasquirt really is the way to go.

You want a MS3 of some sort. There are 3 main vendors. Braineack on here builds them for about $800 shipped, you can find info in the classifieds. Then you can get a MS3PNP Pro from DIYAutotune for around $1200-1250 or something. Then the last is the MS3Basic from MSLabs which is sold by TrackSpeed Engineering.