Ok it's been a few years since I drove this truck and it has issues with low compression on center cylinder on each bank but I've put 200k miles on it like that. The exhaust broke right below the manifold flange so I tossed it an in the scrap and put an aftermarket H pipe on with a duel in out muffler and ran the pipes out both sides behind the tires. 2 1/4 head pipes 2 1/2 out the back. When I did this I put 4 new o2 sensors in. My milage had almost doubled and I've been running it hard cause I like the sound. I'm shocked at the improvement. The only time it's got this kind of milage was getting on freeway and running steady until it needed fuel. I didn't think the stock exhaust was so restrictive. No cats now