Abstract: This invention of a coordinated and integrated fuel and auxiliary-exhaust system comprises, first, of two fuel-line assemblies including their respective controls, and comprises, second, of two auxiliary-exhaust assemblies including their respective controls, said assemblies for internal combustion engines for automobiles, said engines having an even number of cylinders, said cylinders being assigned numbers beginning with the assignment of number one to the cylinder at the front end of one tier of cylinders and said numbering being continued in numerical sequence throughout said tier and throughout any other tier of cylinders in said engine, and said cylinders comprising two groups of cylinders, each group having an equal quantity of cylinders, namely, Group-one cylinders comprising of those beginning with cylinder 1 in the cylinder block in which cylinder the firing-sequence number 1 occurs and comprising of those additional cylinders in which alternately every other firing-sequence occurs thereafter totali