I bought a 2004 Xterra with a manifold leak (a fairly common problem). I ended up fixing them myself. On closer inspection I found that they were fitted to the vehicle at some point with the obvious date code MFG 03/18. I bought the car in mid-2019. For a little over a year, both sides managed to tear along numerous welds. The general build quality also seems pretty poor. I replaced them with a set of stainless steel headers and it's not a job I'm looking forward to doing again. Light work for two days. So I would avoid them at all costs.