im sorry just cat? youre not talking 4" piping are you? just a larger capacity cat right?

 

yessir.



EDIT: and by upgrading to a bigger cat, i mean bigger than the small universal hi-flo Magnaflow cat i'm running, not bigger than factory.

 

oh and are the 99's 235hp or 260?

 

235 in the '99 super duty... 260 on the '00+

 

ok wow....i got some work to do

 

what kind of fuel mileage have you seen?

 

pulling, no idea... it scares me to know, lol.


i get anywhere between 10-12 otherwise.

 

man i cant wait to get this thing and start playin with it. On the hp front, i thought i read somewhere that certain late 99's were 260 hp. have you heard that or know about it? how can you tell the difference between the 99 and 00 motor?

 

It was mid year that they got the increase, exactly when not sure.

 

unfortunately your prob looking at 7-8 mpg while towing something that size and no load the avg 5.4 pulls about 10-12 as bender said

as far as mods go from what I understand you should pick up a programmer on ebay if you can and maybe gears (2wd gives you a distinct advantage over most of us) and leave the rest as is.

Mine ['05 F250 Crew 5.4 with 3.73] has no prob towing but it does rev high. My father-in-law (chevy guy) cringes while we're towing the boat up hill

 

im sold on the programmer for sure, all my research says that at worst ill get better performance and life from my tranny and probably have a direct way to monitor my systems.

regarding the mid year motor change, i think i may be in the good cuz the door jamb says it was manufactured in nov 99. now if i just knew how to find out for sure

 

https://www.ford-trucks.com/forums/563030-pi-heads.html

In the post LxMan1 has a picture showing where to look. (post 6)

 

ok i just looked again and the build date was 11/98 not 99 and the heads have a sticker on them with 10/28/98 and the engine build date. I guess that means i have one of the earliest 5.4's and theres some tuning and upgrades in my future.

 

i was wrong 11/98 for build and 10/28/98 for the engine

 

My understanding is trucks manufactured February of 99 and prior have the 235 hp engines (and were under braked as well), then they figured it out and added a few more HP and boosted the braking as well.

My truck was manufactured in February on 99' and keep having to take parts back!

Enjoy the truck!