I just bought an Edelbrock Performer Intake Manifold.?

It will give you a better air-flow, so your horsepower should go up 20-40hp. You might consider adding a cam to match. Of course then to top the match (howbeit expensive) is to add performance heads.

You'll see some gain, but mostly you'll notice that it will perform best in a different rpm band than it did before. If you're looking for big numbers, though, you have to remember that upgrading one thing isn't going to make much of a difference, because the whole system is only as strong as its weakest link.

Any upgrades from standard will increase performance But i dont think you will notice It will help the engine breath better

You will not notice much unless you port the intake runners on the heads too.