I am always a little leary of performance mods that help mpg. The ones I know of that do in the real world usually lean out the combustion mixture from a little rich, past stioch, to a little lean. But lean is also hot.

Sometimes bumping timing and increasing octane can increase mpg safely, though not fuel cost per mile.

A lot of mods that make more power will eat more fuel, but again, if it shifts the mix too rich instead of burning more it can be washing down the cylinders which is bad.

So what's your experience with mods that make more power on the v-10. What do they do to your MPG?

-Jim