How much of a power gain can I really expect from a Ford Racing 4.6L 3 valve intake manifold coupled with a ford racing throttle body? I have a 2010 Mustang GT with a K&N filter and a roush performance exhaust. It claims gains up to 40 HP, and I kinda dont see how or completly understand. I know its 17 pounds lighter but I do not have any forced induction, cams, or heads. So please help me answer this question, it seems like a good bang for the buck if those claims are true.