Originally Posted by f150country
I'm trying to figure how good is a cold air intake on a 2004 F150 5.4 and what are some improvements I can expect
The '04 F150 5.4L CAI, from I can see, can basically be improved by a "Gotts Mod", which I did, and didn't see any sizable improvement after the mod.
Beware of those snake oil salesman promising big gains, like 20hp, by making changes on a stock / or nearly stock engine using special (expensive) filters and such. The engine will only use what it needs for air flow and unless your filter is normally filthy, gains versus problems will not be on the plus side. Unless your engine is a heavy breathing, chipped, modified turbo'd or supercharged motor running a cam, headers and high flow exhaust, you probably won't see any big change over the Gotts Mod with a clean filter.
A low restiction filter only gets low restriction by allowing larger particles through the filter and catching them in oil applied to filter, but that oil has it's own problems if applied too liberally, which many folks do.