It all depends on if you are going to run a cooled down liquid to air intercooler or if you are going to run air to air.
Air to air won't help as the air cooling the intercooler is the same temp as the air being drawn in from outside the vehicle. Ambient. However, if you are currently drawing air from the engine bay, that's a different story. I recommend just finding a way to install a cold air kit.
Now, if the intercooler is an ice box water to air intercooler or a nitrous halo cooled system, you'll see reduced iat temps and may get a gain. However, I think it would be rather a small gain.
Methanol injection does work for NA cars.