I see so many people running the 14x3 and thats cool but they are around $30 here at autozone/advance. Is there any reason no one runs the smaller 9" ones seeing as they are about half the price? This is really a budget truck and dont want to spend anymore then I have to thanks

 

Probably because they don't have as much surface area for filtration.

You'd have to calculate if a 9" filter is enough flow based on surface area and flow dynamics of the filter media.

 

9x3" filter will give 84.75" surface area (minus rubber top/bottom)
14x3" filter will give 134.88" surface area (minus rubber top/bottom)

The 14" filter has about 60% more surface area.
Will stay cleaner 60% longer.
Air speed going through the filter material 60% slower possibly filtering better.
Will also have about 60% less restriction allowing motor to make noticeably more power

How much did that 9" filter really save you if it takes more throttle to get the same power? (less mpg possibly)
This is one of those cases where bigger is better

 

Factory filter is roughly 13.5 x 6.62 = about 89" surface area and some of the pipeing is smaller then that so wouldnt it be at least equal to stock? I'm not trying to start any argument but just stating

 

If it is equal then why bother wasting your money? I personally wouldn't spend any money on a mod and it still be the same as factory. Spend just a little more and get alot more airflow.

 

What's the point of doing the mod if your getting the same results as you do with the stock intake. Might as well just save your money and not do it at all.
Edit:damn you beat me to it.

 

The stock box is restrictive, even to a stock truck IMO. Going smaller would not be advisable.

 

The surface area makes sense, but the rest of that is ricer math.

 

what's ricer math?

134.88"-84.75" = 50.13 sq/inches (difference in size between the filters)

50.13 (the difference)/84.75 (the smaller air filter's size) = .59150 ~ or roughly 60% increase in surface area over the 9" filter.