As this is something I’d love to do in due course, I’ve read several threads and found this in the faceplace as provided by G19 Engineering, who seem to know a thing or two about options. I copied their post and saved it elsewhere so I could refer to it in due course - such as now!
Clearly, this is doing the job on a budget and there will be some in the forum who decry their methods for reasons they’ll go into but it’s worth being aware that there are simpler, entry level options for FI.
Herewith, their post:
We often get asked what is the best value way to make my MX5 / Miata faster? Here is a recipe of how to make 50% more power for under £1200.
Ingredients
G19 Engineering M45 Super charger kit £576
AEM wideband £176
SPA turbo FMU £100
Uprated fuel pump £40
Used mini charger and bypass valve £300
https://www.g19engineering.com/view.php?cat=79&ViewProduct=180&page=1
Method. (I have linked vids showing installs)
Swap your fuel pump out for the uprated one.
Install the wide band into your exhaust.
Start your car. Note AFR at idle when engine is warm.
Mount and install the FMU in the fuel return line (the one that comes from the stock regulator). Start your car and adjust line pressure adjustment screw until AFR is right at idle.
Install the G19 Engineering Supercharger kit. We would only recommend the standard size pulley on the charger for this set up.
Connect a small hose from your cross over pipe to the signal input on the FMU. This should only see positive pressure. It is not designed to see vacuum so cannot go after the throttle plate.
Take it for a spin. Adjust the rate of gain needle valve until you have 12:1 AFR at wide open throttle.
If you have DET cans you can check for detonation. I have used cans like this to tune cars and bikes with very high outputs. I actually prefer them to electronic ones. Your brain makes a great band pass filter!
If you are not confident in tuning your car, take it to a trusted dyno operator. It shouldn’t take more than an hour on the dyno to get this sorted.