i have a friend with a 06 roush. He bought it as a stage one, but installed the roush blower. with mac shorties, o/r x and axleback the stock blower peaked at 6psi and he laid down 401rwhp, 386rwtq. With the roush pulley, he is peaking at 9psi and made 412rwhp and 404rwtq, but the midrange picked up as much as 30/30. pretty stout car now. Before the new pulley, it was OK. I was at his rear tire from a 40 roll to 120mph and he had 4.10's. . now it is a couple lengths difference.