I just bought a cheap 4-1 header because my 4-2-1 was leaking at the flange.

i get the 4-1 in the mail juat to discover that it doesn't hold water at the seam!!!! Should I even bother putting it on my car to try it? I figure theres no possible way it could hold pressurized gas. UGGGHHH. I just want a not-leaky exhaust system. Or is there some way thar the metal expands just so to prevent leaking?? I just dont see it.

thanks for any suggestions. I know, i get what I pay for

 

Moved to misc/tech as you did not provide model/car information while posting in a model/car specific section.

When you say seam, are you talking a weld seam or a gasket joint seam?