97 460 auto. Have not recorded yet (but I will)
What I do know is the 1-1/2 hour drive I take all the time takes 1/2 tank. Just before i put the banks power pack system on My truck was starting to get poor mpg (took over 1/2 tank) then I cleaned the pcv and fixed some vacuum hoses and got it to do the trip with a little less then 1/2 tank. Now after the banks system it seems like its getting worse - 1st trip over 1/2 tank 2nd knocking on 3/4
Did a tune up last night ( old plugs looked good color gapped .055) I put on motorcraft coppers @ .055, ford racing wires,msd coil and fuel filter. Still need to check timing (might give it a bump)

Bottom line why would it change so much after compete banks system?
Used the old 02s would that have any thing to do with it?
NO CODES - 111

 

How many miles on the truck? An old O2 can affect milage and if it's been in there for a while it's worth changing it.

 

95k. Assuming its original. Maybe taking it in and out stressed it? Even with no codes it might not be working rite?

 

Yeah, my 460 truck is HARD on fuel. I get about 11mpg with the cruise set on 65mph for about 2 hours. I'm gonna try an O2 sensor in the spring

 

Did you purchase banks kit used? Did it come with a ignition module and coil?

 

I bought my kit new and it came with neither

 

Same here. No coil or module.

I'd just check to make sure gas isn't returning to the wrong tank.
And half tank on the front is different then half tank on the rear. Is on my truck anyway.

 

I was thinking of putting BBK shorty headers on my 351W. I've heard nothing but good can come of headers as far as power and mpg. Does this sound like a good plan?

 

Great plan as long as you're doing something with the second cat that's usually plugged.
Others will say longtubes are best, but I think it's a minimal gain for these trucks.
Shortys are fine.

 

I just put a set of shorties and turbos mufflers on my 302. I haven't seen any kind of drastic mileage increase even with new O2 sensor. No cats, true duals out the rear sides(like stock).

Does run a bit better, bumped timing a couple more degrees. Sounds good too.

 

Im mainly doing it for a little custom look under the hood and a little more sound. I figured itd get a little more airflow from the engine too.