^ Agreed 100% Usually takes around 8PSI ICd through an effecient blower to make 420RWHP SAFELY. Alot of the kenne bell guys @ 9PSI dont see 420RWHP. I seriously dont see how your friend did that.
I know the guy you are talking about...he used to post here and Corral. Last year he was putting down 330rwhp then switched to crower st 2 blower cams and went to 404rwhp. He did post a dyno etc but i wasn't there so i can't confirm it.