good point--but--if you are getting 16 mpg now at $4. 00/gal (= 4mi/$) and you were to increase that to 18 mpg (=4. 5mi/$), if the mods cost $1000, in 36,000 miles, the mods would pay for themselves!
36,000 mi/18mpg=2,000 gal x $4. 00= $8,000
36,000 mi/16mpg=2,250 gal x $4. 00= $9,000
I...