A vehicle includes an engine configured to generate power and noise. The vehicle includes a transmission configured to operate in a first gear corresponding to a first gear ratio and a second gear corresponding to a second gear ratio. The second gear ratio is less than the first gear ratio. The vehicle also includes a noise reduction device coupled to the engine and configured to operate in a first state to reduce the noise of the engine to a first volume and a second state to reduce the noise of the engine to a second volume that is greater than the first volume. The vehicle also includes an electronic control unit (ECU) coupled to the engine, the transmission and the noise reduction device and configured to control the noise reduction device to switch to the second state when the transmission shifts from the second gear to the first gear.

An exhaust system for an internal combustion engine includes a muffler, a first exhaust pipe which is connected to the muffler for sound damping, and a second exhaust pipe which extends in terms of flow in parallel relation to the first exhaust pipe and extends through first muffler in the absence of a flow communication with the first muffler. The first and second exhaust pipes originate from a common exhaust pipe. A switching valve adjusts hereby a throughflow cross section of the second exhaust pipe.

A vehicle includes an engine configured to generate power and noise. The vehicle includes a transmission configured to operate in a first gear corresponding to a first gear ratio and a second gear corresponding to a second gear ratio. The second gear ratio is less than the first gear ratio. The vehicle also includes a noise reduction device coupled to the engine and configured to operate in a first state to reduce the noise of the engine to a first volume and a second state to reduce the noise of the engine to a second volume that is greater than the first volume. The vehicle also includes an electronic control unit (ECU) coupled to the engine, the transmission and the noise reduction device and configured to control the noise reduction device to switch to the second state when the transmission shifts from the second gear to the first gear.

A muffler assembly for a vehicle exhaust system including a muffler that has a primary muffler conduit with a primary resonator, a secondary muffler conduit with a secondary resonator, and a valve that directs exhaust flow through both the primary and secondary muffler conduits or primarily through the secondary muffler conduit depending on the position of the valve. The muffler provides a first level of sound attenuation when the valve is in an open position and a second level of sound attenuation when the valve is in a closed position. The second level of sound attenuation is greater than the first level of sound attenuation and therefore the muffler provides a louder exhaust sound when the valve is in the open position and a quieter exhaust sound when the valve is in the closed position.

An apparatus for adjusting power and noise characteristics of an internal combustion engine comprises a wall configured to define an engine cylinder that includes a bore and a compression relief passage. A compression relief valve is configured to selectively adjust fluid flow capacity of the compression relief passage. A manifold is configured to be in fluid communication with the exhaust passage and includes an exhaust bypass valve to permit exhaust to at least partially bypass a noise suppressor. Operational characteristics of the engine can be adjusted along a range that extends from a first set of operational characteristics present when both the compression relief valve and the exhaust bypass valve are in a fully open position to a second set of operational characteristics present when both the compression relief valve and the exhaust bypass valve are in a fully closed position.