It probably has been asked before ... Headers - Cast iron or welded tube? They're going on an inline 6, Chevy 235.
Cast Iron Fenton's would be my choice for the street. Or, if you want to be poor boy traditional, split stockers.
If you are trying for max power, use tube. If you want longevity, use cast. Quieter...cast. More "hot rodd-y" appearance...tube. More classic 50's look...cast. If you have ground clearance, tube...if not, cast.
The Jalopy Journal
