Aftermarket parts in releation to MPG?

[richardholdener]

We have done extensive R&D on mileage gains-oddly enough the most popualr mod (CAI) actually tends to reduce mileage. Hotter induction air improves mileage (but hurts power). U-Pulleys will increase mileage, long-tube headers tend to increase power but larger diameter exhuast systems tend to reduce mileage (I am speaking about cruise fuel economy as measured steady state on the freeway for instance). Light weight or synthetic oil improves mileage, a hotter thermostat improves mileage, larger diameter (or heavier) wheels and tires reduce mileage (and power). As indicated by cali-the single largest difference in fuel economy is driving style. Basically, the less you step on the gas (or change throttle angle), the better your mileage (ditto fro slower vehicle speeds)

Originally Posted by 4MPG

Has anyone done a before/after of MPG after doing some of the simpler performance mods (CAI, NST pulleys, etc)? How about any cars setup kind of like the "richard holdner" car?

I would think at least the CAI/Pulleys would actually help, and maybe even the exhaust/intake parts as well?