I've still got the same car, and still enjoy it, despite a few wear and tear things popping up.
And also having done the old "learn from experience" thing.
One of the main things I've wanted to do is give it a bit more grunt, since it's noticeably lacking.
The original plan was to build the head, use some big-ish cams, and then when the bottom end finally goes boom, build that bigger (ideally bore it out ~2mm to bring it to about 1920cc or whatever the maths works out to be, but that would depend on budget)
Step 1 would always be to organise an ECU so that, well, it will actually run with those changes.
The plan was to install that and tune on the untouched engine to iron out issues, then move onto changing bits.
And here's where the problems started...
I purchased an Adaptronic ECU since they had local support, and also a tuner near me who both tunes them, and also has a name for being one of the best tuners in the state.
Turns out he was rubbish at it.
First tune the car would lean out when the throttle was applied slightly fast, it also had severe idle hunting and would often stall.
Second tune he fixed that, but at high RPM shifts it would misfire. Also on cold mornings it would flood (not just a little, i'm talking backfire out the intake, and shoot 4 feet of flame from the exhaust before hydrolocking)
Third tune he'd fixed the start, well, it started at least. But the throttle was back to how it was at step 1.... and light throttle was absolutely undrivable.
Fourth time he emailed me a few tune files with someone else's name on them and a story about "sorry for that, got the name wrong but they're your tune files i've changed" I knew that was BS, since the MX5/Miata community here is pretty small, and even though I dislike most of them, i do know them.... he'd sent me someone else's tune... Fine with that, but dont lie to me, just tell me that's what you've done.
I ended up managing to tidy up the tune a little to at least be drivable, if rough, in about 10mins in my driveway.... when looking at the tune it was all over the shop. Mainly the predictive MAP for the transient throttle settings. They're supposed to taper with RPM/Load etc.... he'd just made an arbitrary guess at 120kpa across the board (worth noting, 120kpa is positive pressure compared to atmosphere, which isn't actually possible on a naturally aspirated car)
So yeah, after all that with the tuner I just gave up on him, 4 visits, and some lies, and I still got a car that ran like garbage.
I'm at a crossroads now.
The ECU has been removed, advertised for sale, and the factory one put back, since it runs great on the un-modified engine.
But I need to decide now where to go.
Get a different, better supported ECU (and a better tuner)
Or just give up and leave the car standard and deal with it being slow.
Still looks nice at least, and now handles well again since I replaced the faulty brake proportioning valve (doesnt brake too well when the valve is stuck open meaning the rear brakes werent doing anything)