The HEMI diehards called it an angry mosquito from the moment they heard the fake V8 sound, produced by the Fratzonic Chambered Exhaust ... cars after owners complained that the hood would not pop ...

Read more: 6 American Cars With JDM Engines Under The Hood Although ... be connected to active exhaust systems. These use internal valves to control which pipes are open and how the gases move.

Unassuming inside and out, this plain-looking 1959 Plymouth Belvedere hits the road with a 500-horsepower Dodge Viper engine.

These elements may feature open faces or butterfly valves ... and are often visible above the car's hood line. So why do so many muscle cars have these, and what's their role in the process ...