Like it says, will mileage decrease with a short ram intake or a CAI ? If so how much ?

yea and no.

Now you have slightly more hp to get up to speed, so if you keep the revs low you'll gain hp. Too high tho, and the added amount of air you're sucking in will cause the ECU to addmore fuel in, therefore less miles per galloon

A turbo, if you keep the RPMS too low you'll muck abot in vacuum; and will waste lots of hp. Keep the rpms right after you spool, and u should be nearly perfect- the rpms too high will dump fuel in.

I have a 94 st.. an when I added my cai.. It almost seemed like i got better numbers.. witch im guessing it didnt change at all for the worst that is. but I dont think its going to give you better.

i'll tell u straight up, when u first get it u will drive it hard because u will love the sound of the intake and that will cause your gas milage to go bad and after a while u will stop driving to hear the sound and it will go back to normal. either way it wont help u any.