Proper exhaust-pipe size is a function of both engine output and displacement. The higher the engine's output, the larger the pipes should be. Likewise, larger engine displacements call for bigger ...

So, for instance, a 200 cubic-inch (3.2-liter) engine with 250 horsepower would require a 2.5-inch diameter exhaust pipe. Or a 250 cubic-inch (4-liter) engine with 300 horsepower would best match ...