Our cars are not naturally aspirated, so you can't just assume we get the same gains...and that's on a V8 making significantly more power to start with...and it's only 'up to 13hp', not a guaranteed amount.
Holy crap, $600+!!!
Edit: Let's do the math and assume that for some reason the gains are constant between the Coyote and our Ecoboost.
13/412=0.031553
0.031553*197=6.31
So $605 for 'up to' 6.31 hp, or just a touch under $100 per hp.
Worth it? That's for the end-user to decide. And realistically speaking this math exercise is completely irrelevant because we don't have a normally-aspirated V8. Maybe we get more, maybe we get less. Either way, nobody is going to know without some legitimate before/after dyno charts.