If you are asking whether you can get 20-30 hp at the engine from a proper exhaust, intake, and removing the cats, the answer is yes. However, I don't think you would get more than 10-15hp at the wheels. You may also see a boost in gas mileage, though you may lose a little low end torque.Came across the following post at TOCAU.
The OP claims HP gains of 20-30. Your comments on this please.