i am unimpressed with the hyd roller i put in my 440. since then I've been searching for dyno #'s on Big block mopars with hyd rollers on the net. looks like they all start to give up around that 5800 mark give or take a few hundred rpm. that's about where mine fizzles. it runs like a bear up till that point. a set of beehive's might help it but im pretty disillusioned. it'll twist higher but its just not there. i think they're perfectly fine for some one who just want to cruise their car around. or even a low rpm stroker. i hate to give up on mine because it wasn't a cheap proposition, but it will probably be coming out this winter for a solid.. unfortunately it wont be a easy swap with my home made valley tray... got a .557 cam brand new in the box, thinking that might give it the kick im looking for.