For a 383 stroker engine, a typical exhaust pipe diameter would be 2.5 inches; however, depending on the specific application and desired power level, you might consider a slightly larger 2.75 inch pipe for optimal performance. google it
~ BD. "You won't find me in an old folks home" Pioneer Florida Cracker 1958 Apache Stepside 1958 Apache 1/2 ton Panel 1959 Apache 1/2 ton Panel