I must have a heavy foot...my 95 (X-cab, 4wd, 285's, E4OD, 4:10's) has always gotten 8mpg whether its towing or cruising. It recently moved up to 9.2 after having the trans rebuilt, but it stays around 9 no matter what.
I know technology has advanced but I do love my 460, this has been the best truck I've owned.
my 97 4x4 460 has set the bar really high for reliability and I'm kinda scared to replace it after 13 years of ownership plus my friends wave at me now and if I traded trucks it would be 6 mos before they would know who I was.
Used to have a '97 F250 4x4 460 auto regular cab all stock, awesome truck, used to get 12.5 mpg empty or towing. Sometimes I miss it but I'm addicted to diesel now. Truck had 153000 miles when sold with no problems.
part of the problem w/yours might be te 35's, the taller the tire the greater the gear ratio, so if youre runnin 4.10's, it's more like 3.55's now, especially when you figure that truck came stock w/235/80/16's (rough guess), and those 35's are the equivelent of 315/70's...thats a big jump, and can caouse alot of problems if not done right.....at a bare minimum i hope they flashed the OBDII when they went that big, you might get that looked into.
as for the "air horns", look @ the air tubes from the filter box to the engine, adout 1/2 way theres a plastic junction, the horns are hid in the hose on the filter side of that junction, simply pull the hose off, and saw the horns off (leave enough plastic to clamo the hose back onto).
as for MPG since i did mine, I'm up to 12.8 runnin around here empty, 13.6 on the interstate empty, and 10.2 with a 4000# load on my 20' trailer (total of 6000#) on the interstate.
not bad considering stock it got 10 empty, and 7.2 loaded (same load).
If any of y'al are looking @ rebuilding your engines, and wantin "good" mileage and still keep some power, lemme know and I'll post exactly whats been done to mine for you to kinda follow....I'm sure the external mods would help some too, but i think alot of mine came from how it was built, especially if you look @ the numbers and keep in mind i beat the hell out of this thing, if i could keep my foot out of it i might gain another mpg or 2, who knows? (the pipes sound too good to try to find out).
Can you please send me tell me how yours was rebuilt to have better gas mileage. Thank you so much!