The hp limit is the turbo if you use a turbo that only capable of 900 hp that will be the total output just a different boost amounts eg.. a 300 Hp NA engine needs about 22 psi of boost to hit 900 hp and a 600 Hp NA engine needs about 7-8 psi for 900 hp. Point is you probably don't need special heads to accomplish your goals.
Correct and I agree. These W5s are ready to bolt on for the same price as it would be for me to outfit my edelbrock heads thus why they peaked my interest but I do agree