Your 2003 F150's catalytic converters do NOT cause any extra fuel usage, and your engine depends on them to run right. Federal law prohibits removing them, although I've never heard of that federal law being enforced. Depending on where you live, your state or county may strongly enforce their own law preventing the removal of catalytic converters.

So, that said...if you wanted to break the law, you could spend the money to get them removed and spend the money on a custom tune to make your computer ignore them, but it won't improve your fuel economy.

Are you more interested in modifications or in learning driving techniques?

I was looking more for modifications. I'm pretty sure I would hate myself if I had to drive little 4 banger everyday, plus I do have a few trailers I pull on occasion.

There are some modifications that can be done, but most either are very ugly DIY jobs (which doesn't bother some of us, but I'd guess that they wouldn't work for you) or will never pay for themselves.

warmer air intake, move your intake to be closer to the engine somehow(make sure the air is hotter than before!), and use clear caulking around your headlights to keep the hot air in (making sure your cooling system works properly) dont over inflate these tires you dont want to crash that truck maybe and extra lb of air, and get a rear cover, just those ones that roll up help aerodyns

two points for me

dont cut off your cat you will be doing harm to the environment probably triple the emissions, hell, the smog could even choke you out at a red light from a 5.4 hahahaha how does lung cancer sound?

also stay under 1600 rpms, staying under a certain rpm during 0-40mph acceleration helps you get into higher gears at lower speeds try going into highway gear at 36-42mph, plus it increases the longevity of your transmission

this is where your biggest gain will come from
you could get an easy 20mpg like this

Good points, spotaneagle. I disagree about the tire pressure, though. My 2002 GMC Sierra 1500 4x4 (similar truck) handles far better with 60 PSI than with the recommended 35, and at 80 front 70 rear it handles about the same as at 35. The ride quality is not affected in any way I can detect. I have Load Range E tires which are rated for that high pressure; OP probably has P-series tires rated for 44 or 51, and that maximum pressure will be fine.

I have E rated tires on my K1500 as well. The max pressure on the tire sidewall is 80 PSI, but I've been running them at 70 PSI and the tires are showing no abnormal wear, and its riding and handling well.

yea i dont own a truck i dont know about tire psi, my new idea?????

iss.....

drumroolllll


Seal-and-Peal caulk on your lights to keep in the heat and help aerodynamics in the front, seal and peal is a semi-permanent caulk that you use in the fall and remove in the spring on leaky windows in your house, it doesnt take alot of house paint off with it usually would probably not take much car paint off at all, no worry's if its plastic or chrome, that way if you ever want to remove it you can

Cool. I've never heard of that but I ought to check it out.

Well I've been doing my research and I found a hell of a deal on a beater car, it says it has a 390 FE motor. Does that stand for fuel efficient?

Here is the car I found.
https://www.stationwagonforums.com/fo...marauder_2.jpg

I'd roll it!

...and of course the FE stands for Fuel Efficient. Isn't that what all big-displacement antique boats are about? :D