The Arduino Nano-controlled 2-Manifold Absolute Pressure Sensor circuit was a home-made effort. I didn't design it, got the idea and a lot of help from a guy in Germany.
Small, high-revving pistons of small motorcycle engines (like the EX250) produce really jumpy-jagged-messy Manifold Absolute Pressure signals that aren't very good for input to an ECU.
This circuit monitors each of the two cylinders individually. On a millisecond-by-millisecond basis the circuit determines which of the two cylinders is producing a lower signal (i.e. pulling more vacuum) and it send only that signal onward to the Microsquirt ECU.
This discrimination smooths out the MAP signal for the Microsquirt ECU.
In this picture:
-the 2 rounded black plastic items are the MAP sensors
-the green item is the Arduino Nano
-the red item is a Digital-to-Analog converter
-the brown item is just a piece of basic circuit board to hold/connect the items (lots of wire and soldering)
I put the whole thing into a weather-proof plastic project box.
Not shown in these pictures are the rubber hoses that connect the MAP sensors to ports on the throttle body.