For MIG welds, they are ok, could be better. They have no cleanup marks on them, so they were welded once and done. For the amount of money they cost, I would have liked to see them TIG welded. One other thing I did not like about these headers is the bends in them. The drastic bends are mulitiple pieces of mandrel bend, whichs is fine, but there are a couple of compression bends on the primary runners on mine. These headers are 1 5/8 primaries, so that means the are SLIGHTLY smaller on the bends. Maybe I am just too pickey, but overall I am happy with mine just because they fit so perfect.