Horsepower guess?

The Magnum doesnt use the AIR injection holes. I agree with the 300-325hp. A good solid street engine. The stock magnum type valvetrain does not work well with valve lifts over about .490 with 1.6s. I think you'll be happy with it, but like the others said... by using the KB flat tops for another hundred bucks over stock, you will get a better output all the way around and I'd estimate a pretty easy additional 25hp over the stock ones. Stock pistons yeild about 7.8:1 when it gets figured with the factory heads. Add Magnums and it will go up to about 8.3:1.