Remove stock ecu and bracket, plug in your new DIYAutoTune Megasquirt PNP MM9093 , bolt it down, run Map line to intake, pull ST SGN 10 amp fuse, start car, goose it a couple of times, hit the kill switch, eat sandwich while looking at the car, congratulate yourself on how clever you are generally, and specifically in this case, how you exceeded your own cleverness expectations. All this for the price of a set of go to the race tires. Of course, an interface in the form of a laptop (cable included) and a dyno (not included) would be required to further optimize for your engine.
The dyno sheets as posted by Jerry indicate that the device as configured by DIYAutoTune does improve torque and hp across the range significantly. The air/fuel ratio is controlled by the unit and the AFM could be tossed for more gain. Someone may notice this missing in SCCA impound.
Jerry and the folks at DIYAutoTune have an impressive product line and development facility, and are definitely focused on customer service.

Joe Tenney
90 Miata ITA.