Can you tell a difference with a mass-air flow air sensor on a ford exp. 5.4L 02'? And if so how much is it, and how much horsepower would i gain from it?

 

I was told not to worry about changing the MAF sensor by Sean Hyland Motorsport. They said that for around $350 you may gain slight in the hp's, but for a stock truck, not worth it. Some actually loose power. Only a Lightning or built up engine really benefits. A chip or programmer will give good results for the money.