ok, I think you meant Cold Air Intake for CAI. I am assuming you mean Warm Air Intake for WAI. Don't know if that is what you are referring to , but it's normally called an SRI - Short Ram Intake.
You might gain 1-2WHP with an SRI, maybe 2-3WHP. Honestly I doubt it. Better throttle response will make you think you've gained some horsepower though.