I have a 2001 f150 super crew 4x4 and it has the 4.6l in it and I put flowmaster 40 series in it with a E-tip and it helps my MPG and it feels like it has more power but I was wondering if I make 22-23 on the highway and 14-15 in the city if I put a cold air intake on it how much difference in gas milege would it make? and how noticeable would it be driving? all the intakes ive looked at don't have a cover on the filter? I go mudding now and then would this be a issue ?

 

It will have "0" gains in HP and MPG.The factory intake is the best for a truck.

 

correct......... all after market "cold air intake" are a waste of money. The factory intake is a "COLD AIR" system.

 

What's not being understood is you cannot break into a computer controlled system to effect these kind of changes with an air intake or exhaust change.
It's all program controlled using input sensors and output control.
An air filter in not one of them.
Good luck.