Maybe some feel good magnets on the fuel lines as well? Or turbulators in the incoming airstream? A computor chip should also give you another 100 horsepower and up the milage at the same time. At least we should grease the face of the tires to reduce rolling resistance regularily.

The fact that there is no place to plug a chip in is irrelevant as long as you buy one. I visualise that whole area as a million dollar industry for some people out there. Sad but true.

A 617 can make 40 miles per gallon easily but you have to go over a cliff to get it. So it is more or less a one time event.