My wife and I recently bought an '09 Expedition Max with the 5.4l motor. After fueling it for the 4th time in 6 weeks, I was wondering if anyone has any experience with cold-air intakes, exhaust system upgrades or the various plug-and-play programmer chips, with the goal of more power and maybe a few more mpg's. thanks
The exhaust and intakes will do little or nothing without a custom tune. Even with a tune, you won't see a noticeable increase with either. For MPG increases, the intake is a waste of money. Look at the manufacturer's sites; most show the hp increase at over 3500 RPMs. If you're trying to save gas, why would you be at 3500 RPMs?
You can get custom tunes (which will provide the most hp increase) via e-mail/download.
The most experienced and reputable are SCT (can be tuned by VMP, PHP, and Troyer) and the Gryphon (tuned only by PHP).