Albert Widmann with the car engine running. He had nearly died of carbon monoxide poisoning from the exhaust fumes. This engine exhaust testing inspired the development of gas vans. Back in Berlin, Reinhard Heydrich immediately set to work within the RSHA for the development of, in the words of Heydrich's subordinate Walter Rauff, a "more humane method of execution" than the "Einsatzgruppen" firing squads which had been used. When a prototype gas van was driven to KTI, Widmann explained to his young chemists that by adjusting the timing of the ignition, one could maximize the amount of poisonous carbon monoxide in the
Aftermarket exhaust parts where the exhaust gas velocity causes a slight vacuum in another header pipe. This has an effect of scavenging exhaust gas from the cylinder, which is beneficial for performance. In performance engines, which have cam overlap, the scavenging effect will pull air through from the intake manifold as well, further increasing performance. The length of exhaust headers can be tuned to perform best at specific RPM ranges. Stock exhaust manifolds are usually made of cast iron and can be restrictive. Headers may or may not increase the dB level of the exhaust, depending on the original exhaust manifold it replaces