This is somewhat old here but I do have the ATS kit on my truck, and I don't believe I carry 3 psi at highway speeds. When I installed the kit I tested it on a long hill nearby and I was not able to carry any more speed at the top than before NA. I have not turned up the fuel yet that is my...
About 10 -13 years ago I had a 94 c 1500 Ex cab short bed that I bought a complete exhaust from Heath and installed. The down pipe needed minor mods but worked well with no leaks.