New certification documents released by the California Air Resources Board and the Environmental Protection Agency reveal Harley-Davidson is adding two new “S” variants to its Fat Boy and Softail Slim for 2016.

According to the CARB executive order, the new 2016 Harley-Davidson Fat Boy S and Softail Slim S will be powered by the air-cooled 1802cc Twin Cam 110 engine. Returning for 2016 with the 1688cc Twin Cam 103 engine are the regular Softail Slim and Fat Boy, the Fat Boy Lo, Softail Deluxe, Heritage Softail Classic, Breakout and Street Bob.

Certification documents from the EPA also confirm the two new S models for 2016, rating them at a maximum output of 80.5 hp at 4000 rpm compared to the EPA-rated 76.4 hp at 4000 rpm for the 2015 models with the 1688cc engine.

In recent years, the 110 engine was only offered on CVO models or as an optional add-on kit. The S variants of the Softail Slim and Fat Boy may be a mid-level upgrade that slots in between the base models and the top-of-the-line CVO versions.

Beyond the larger engine, it remains to be seen what else Harley-Davidson added to create the S models. Harley-Davidson tends to make its new model announcements in mid-to-late August, so expect to hear official news soon about the 2016 Fat Boy S and Softail Slim S.