Abstract: The disclosure is directed to an exhaust efficiency increasing apparatus incorporating crossover ducts between dual exhaust conduits extending from an engine having two cylinder banks. The ducts are disposed to communicate with upstream entry and downstream exit apertures on the exhaust conduits and cross in an "X". Since where the ducts are positioned affects engine torque, torque curves can be adjusted or changed by adjustably positioning the crossover ducts within a housing which is placed in the exhaust system, to move the crossover ducts nearer to or further from the engine, by computer or manual control. A second embodiment incorporates at least two spaced duct pairs disposed to increase low end torque and high end output.

Abstract: The disclosure is directed to an exhaust efficiency increasing apparatus incorporating crossover ducts between dual exhaust conduits extending from an engine having two cylinder banks. The ducts are disposed to communicate with upstream entry and downstream exit apertures on the exhaust conduits and cross in an "X". Since where the ducts are positioned affects engine torque, torque curves can be adjusted or changed by placing the crossover ducts near one end of a housing which is placed in the exhaust system and which can be reversed, end-to-end, to position the crossover ducts nearer to or further from the engine.