Another disadvantage of flat-four boxer configuration is its requirement for long exhaust pipes merging the exhaust from those exhaust ports located on opposing banks in order to achieve evenly spaced exhaust pulse. In a four stroke engine, each cylinder creates an exhaust pulse every 720 degrees of crank rotation, and they need to be paired with another pulse that is 360 crank degrees offset in a four-cylinder configuration to achieve an even scavenging of exhaust gas in the cylinders, which is needed for uniform filling of intake and uniform combustion.