These Hemi 6.1 manifolds do not align well with the heads so I am matching them both to the gaskets. From reports I have read it gives an extra 20 HP at 4500 rpm, not sure that I will ever use the 450 + but it will also give me a little in economy. I have roughed it out, now need to tidy up a bit. I made the mistake of wearing gloves and the big die grinder grabbed one and wrapped it around my wrist, ouch, no skin off but those things have some torque !.
