[piecesparts]

Several things involved here. #1. Headers will sound different, under the hood and while driving, due to the fact that they are made of a thinner material than a cast iron exhaust manifold. There will be some exhaust noise coming from a perfectly sealed set of headers. #2 The sound of your supposed leak can be defined as an exhaust manifold gasket or a collector gasket by two things *is it around the head area and is it a single ticking sound rather than a more continuous sound. #3 If you have a leak, then look at the exhaust gasket and there should be a trace of carbon where the leak is at. I personally use Felpro gaskets and I coat them with "Copper-Coat" gasket sealer for longevity. I put teflon tape on my header bolts to keep them from backing out once tightened and set for use. The teflon works great and it will keep the bolts where you tighten them to. Once the header is on, then start the engine and warm everything up and do a final snug tighten on the bolts. I have headers on most of my vehicles and have not had any leakage issues for many years of use.

All of the below have headers and no leaks

84 GMC Sierra 383 stroker
85 Chevy Silverado 350 crate engine
2011 GMC Sierra (daily driver) 5.3
95 Chevy Impala SS Lt1