Exhaust Baffle (dB Killer)

An exhaust baffle is a perforated tube, plate or chamber inside a silencer that breaks up and slows the pressure pulses of the exhaust gas, making the bike quieter. In absorption silencers the perforated tube is wrapped with sound-absorbing packing such as glass fibre or steel wool.

Many aftermarket exhausts have a removable baffle, often called a dB killer. Taking it out makes the bike louder, can change the fuel mixture and low-rev torque, and usually makes the exhaust illegal on the road. Many off-road tracks and competitions also have strict noise limits.

If an exhaust becomes louder and raspier over time, the packing has probably burnt or blown out. Repacking is a normal service item, especially on two-stroke and motocross silencers.