don't look at peak power gains.

Look at the dyno and the rpm range you'll actually be driving in. If that's what you want, then get it. BTW 2-6 hp gains are hardly noticeable, even if they are there.

If you want the most dramatic change, do intake/header/exhaust all at once. Then you'll notice the difference... for about a week. Then you'll want to go turbo or swap.