My 2001 Dak 4.7V8 developed the usual failed stock exhaust manifold crack back in 2014. I bought a used set of Gibson shorty headers that fit in place of the stock manifolds. Had them installed with new gaskets and stainless steel bolts with the anti-loosening lock tabs. Before I had the headers installed I had them shot cleaned and ceramic coated. They were installed back in early Sept 2015, been great ever since. Never loosened, never had to be re-torqued. Never developed any issues, can't say they improved fuel mileage but certainly never made it worse. Power wise it may be a bit better above 4,000 rpm though I don't get there too often. Oh, and I live in Green Bay so in the winter the road salt and brine applied to keep the roads clear are hell on the old Dak but the headers still look good. So all in all it was well worth it. I would do it again.