very little if any indeed. you may have picked up a few hp at the crank but nothing that will actually improve performance at the wheels (rwHP).
for a cold air intake to be effective it really requires:
1)a proper exhaust system -not an axle back...in your case full exhaust - catbacks with an x-pipe , true duals (like the new bassani for late model v6 mustangs...you can see the installation on you tube, just search "mustang v6 bassani"
2) headers and then
3)retune the engine management system with a tuner chip.
with those modifications you will pick up in the range of 15% increase over stock power and with the headers much of the power will get to the wheels making a noticeable difference in the drive....then if you install 3.73 gears in the rear end you will really be quite quick from the get go.
....your present installations are basically doing nil at this time and without performance exhaust and headers really a cold air intake is a waste of money.
probably around 5-10.
get it tuned (which you really want to do, as those 4.0s pretty much need a tune after a mod, even if someone claims it doesnt. you may be able to run for a little untuned, but it seems like people run into problems down the road) and you could realistically gain 20 or more