Diesel JD said:
You should still do the ATS turbo upgrade, if you mean switching the downpipe from that squished one that they gave your factory turbo truck for a real downpipe, then you will see some performance gains. I plan to swap over from the 4.10s to 3.55. My heaviest towing is about a 5000lb boat or hauling a cord of firewood on flat land, generally. A turbo is hopefully in my future too, but I am getting tired of 10-12MPG towing or 13-16 empty. If I could get 14-16 around town and 17-18 on the highway I would be real happy. I have the 3.55 axle laying in the backyard, I just have to clean it up and get with somebody to help me do the swap.
J.D.
I know the high-flow downpipe would open things up a bit, but its also expensive and a pita to install.
You can swap the axle yourself - I did mine by myself in my driveway in the rain at night, wasn't exactly fun but it didn't take long
If you can afford it go for a gear vendors overdrive rather than the 3.55's - if not the 3.55's aren't bad but you will looose a little acceleration.
My first tank with the 3.55's I averaged 15.7mpg and most of that was either in town or towing my motorcycle trailer around in hilly areas. I generally set the cruise controll at 65mph. I expect that the next tank will be a bit better, but we will see.
You should be able to get the mileage figures you want now if you just stay out of the throttle a bit more and limit your top speed to 55mph. I don't think I'd like 3.55's without a turbo - with the turbo it seems like it has just enough power to pull them comfortably if you do much towing in hilly areas (well, I guess that's not an issue in FL).
