Generally speaking the dyno tests I've seen for the XV, Modman, Mopar Performance, and 08 and before 5.7 and 6.1 manifolds tend to show that the short runner XV, Modman, and Mopar performance tend to give up A LOT of midrange torque but make more HP at the top end when compared to the stock 5.7 manifold. The 6.1 on a 5.7 tend to "split the difference." Though the one test I can remember clearly did not port match the 6.1 manifold to the 5.7 which may have cost it some HP.
Which manifold has more area "under the curve." is somewhat unclear.
