Malibu Boats’ new Monsoon M5Di and M6Di engines achieved the highest certification through the California Air Resources Board. The level-five “extremely clean” designation gives the M5Di and M6Di the lowest emissions rating possible.

“Direct-injection technology and the design of our exhaust with a three-way catalyst has allowed us to be able to calibrate to lower emissions than ever before,” said Malibu drivetrain lead engineer Scott Peterson in a statement. “We also have the only fully integrated heat exchanger in the industry, which includes the oil filter, transmission cooler and heat exchanger all on the closed-cooled circuit. This makes for unmatched durability in brackish or salt water and lower engine temperatures for better efficiency.”

Level-five emissions are at least 50 percent lower than the four-star “super ultra low” rating.

Malibu said it was able to achieve this by taking its engine production in-house; the company has a 70,000-square-foot engine manufacturing and-test facility next to its boatbuilding plant. Malibu says this allows it to control the entire process from start to finish.