There is some debate over whether a straight pipe exhaust can damage an engine, but most experts seem to agree that it can. Reducing the backpressure with a straight pipe exhaust, can in some cases cause your air-fuel mixture to run lean, which can damage the engine's internal parts. It may also increase the horsepower and torque of your car engine, which it may not handle well. Therefore a tune is recommended after installing a straight pipe exhaust.