Eminent18

I have a 98 gt and I've been looking for a good set of heads because everyone agrees that heads a great basis to begin with when you are going to build a car for power. I've seen one set in the ford performance catalog that said you would get 35 extra horsepower. For a thousand or so dollars I'm thinking 50 to 100 pony's. Does anyone know of such heads. Can you put the cobra's heads on a gt and would that give any horsepower if you could..