well i bought a used header froma friend. it was cheap, but it was a 4-1 race header. i put it on and bolt it on and i noticed that i see a lil smoke come out of it when i rev it. so i rebolt everything aagin jst to make sure. i see smoke again and i can even hear an air pocket when i rev it. it did this the first time as well. so im thinking that my header maybe A. warped a lil at the top, or B. there might be a hole where its been welded. do u think im correct, and if its warped, i can take it to a machine shop to get it fixed?

 

if u haven't try using a new exhaust manifold gasket