Post number 1 you say a 9 speed. Post number 11 is now a 13 speed, or to be accurate the 9 speed converted to a 13. you do the conversion from post 2-10?
Swap or convert the nine speed for a thirteen speed. Keep the 3.70s they will pay off in the hills. The cat will not get you that much more if any mpg but it will make you go faster and get up hills easier.
thing i was looking to get both worlds..lower my rpms for a lil better fuel milage and power when i need it...i dont do alot of hill if any hills..i run miami fl to jersey,pa and back, but now im runing 1550 at 66 to 67 and im doing 5.4mpg.i would like to get 5.8 or 6.0
Keep in mind, you've stretched it, and you're now dragging a sail in the wind with all the air that's slipping between the truck and trailer... If you've gotten it back up to 5.5, I don't think you're gonna get much better no matter what you do..
before i raised the hp to 575 with a new program to the ecm i was getting like 6.2 same set up, but it was weak
