Straight pipes

Straight pipes are exhaust pipes with no baffles, packing or silencer, so the exhaust gases flow straight out. They are mainly seen on custom cruisers and choppers, chosen for the sound and look.

The performance gain is usually small or even negative, because the loss of back pressure and changed exhaust pulses can hurt low and mid-range torque, and fuel-injected engines may run lean without remapping. The noise is extreme and tiring on long rides, and can damage hearing.

In the EU, road-going motorcycles must use type-approved exhausts and meet noise limits, so straight pipes are not legal on public roads and can lead to fines and a failed inspection. They are only suitable for closed-course use where rules allow.