Cold air intakes gain 2-3 horsepower MAX on a close to stock or semi-modded car. I've seen them actually lose horse on a dyno because the metal heated up so badly. The only cold air I would ever buy would be a densecharger. (no longer made) They were made of hard plastic and actually showed sufficient gains in horsepower. No, not 10+ but around 5. I had one of the metal bbk ones on my mustang for about 3 months, it made a terrible whistle (not into all the rice noises) and it hit my engine mount bars when my engine throttled. And on my mustang, i'd assume the BBK cold air I had gained me 1 hp, only because of the new k&n filter.