VARIATIONS
Exhaust systems can either be single or dual. Dual exhaust systems have two exhaust pipes to carry exhaust gas from the engine. Such systems are used with large V-8 engines, since larger engines produce more exhaust. Single exhaust systems are used with smaller 4 or 6 cylinder engines, especially of the "I" (straight) block kind. Dual exhaust systems are louder than the single type, but they also permit the engine to produce more power since exhaust gas backpressure is reduced.