I'd like to improve the mieage of my 97'F350 two wheel drive 7.3/auto. My routine drive is 15 miles/day only 2 on the freeway.
I do accasionaly tow a boat (5000 lbs)
The actual question is: if I was to pick away at the opportunities to improve the mileage, what would be the dollars vs benifit. Such as exhaust runs $400-$600 and improves the gpm by??? A better breathing air filter runs $120-$150 and improves the gpm by???

Can you guys help me prioritize my $$$$

 

I think this would help you mpg wise the best...
1. Just replacing the downpipe with a 3" round one, and gutting the cat. ~$120. +.5-1 mpg
2. Adding a napa 6637 filter and getting rid of the stock intake. $45. +.5- 1mpg
3. Getting your pcm reflashed wit a mild tow/ economy tune. $200. +2-3 mpg
4. Pump your tires up to 70psi. FREE. + 1-2mpg depending how low they were
5. Keeping your foot out of the throttle as much as possible.

I have seen 18 mpg going 70mph with my 4.10 gearing, and 12 mpg going 90+ mph down the highway. Keep the speed down and you will see a boost in mpg. I got my best mpg of 21 mpg doing 55mph.