How much hp does a intercooler add to 99 cougar?

Answer 1

It all depends all cars are different, your same here and model car could have the same intercooler than you and push out more or less than yours

To add to this:

An intercooler will not add any HP to any car. It will allow a turbo/super charged engine to make better use of the charged air. (It cools the air, and the molecules of cooled air are more densely packed than warm air.

What this means is that more air will go into the engine with cooler air, and thus will allow the car to inject more gasoline per stroke. So the same energy is still there, you are just loosing much less to heat.

Since you have a 99 Cougar, you don't have a super/turbo charged engine, and thus don't need an intercooler, unless you have added one of these to it. An intercooler on a non FI car, will lower performance, not raise it.