I have a 04 F150 5.4, and i had, what i thought, was a Flowmaster 40 series on. but my local muffler shop slid the knockoff version on without telling me. So taken to another shop this morning, with the y-pipe cut out and true duals all the way out. it sounds amazing. Just wondering if anyone has pictures or a walk through of a header install. i'm looking for a little more low end, and maybe a little more noise.

 

Use the search option. Tons of header info here...