Abstract: An air intake assembly for an engine of a motorcycle includes an air intake opening for receiving intake air, the intake air defining an air flow direction. The air intake assembly further includes an airbox at least partially defining a chamber. A partition is positioned within the chamber dividing the chamber into an expansion chamber in communication with and downstream of the air intake opening and a sub-chamber configured to reduce the noise associated with the flow of intake air through the air intake assembly during operation of the engine.

Abstract: An exhaust system for a motorcycle engine includes a muffler assembly. The muffler assembly includes a downstream attenuation portion adapted to be positioned substantially rearward of the motorcycle engine and having a first height, an upstream portion adapted to be positioned substantially forward of the motorcycle engine and having a second height, and an intermediate attenuation portion between the upstream portion and the downstream attenuation portion. The intermediate attenuation portion is adapted to be positioned substantially below the motorcycle engine and has a third height less than half the first height. In some embodiments, a motorcycle is provided, in which the motorcycle engine is positioned substantially within a recess of the muffler assembly to a depth greater than the third height.