The document points to slight revisions to the engine internals, intake system, valvetrain, exhaust and combustion chamber.
Corroborating recent rumors, a leaked Mazda document appears to detail technical changes for the 2019 MX-5 Miata.
The upgraded Skyactiv-G 2.0-liter engine jumps from 155 horsepower to 181 ponies and 151 pound-feet of torque, thanks to a lengthy list of small changes.
The engine has received ultralight pistons, lighter connecting rods, and a rebalanced crankshaft to achieve higher rpm operation. The intake system and valves have been enlarged and paired with a smoother manifold, while the exhaust valves have also been reworked for improved flow.
Engineers modified the combustion chamber, reducing piston height and improving air movement and injector atomizing efficiency.
Aside from the upgraded engine, the 2019 edition is also due to receive Mazda's latest safety technologies including Smart City braking, traffic sign recognition, and a wide-angle backup camera, among other changes.