The old mopar cams sell so well because they work OK and they say mopar on the box. The newer desighn cams work better and are cheaper but people think for some reason that useing a comp or lunati is like putting a chevy cam in their mopar when really it is quite the oposite, the old mopar cams are lobes stolen from chevy desighned cams that have to use the smaller lifter diameter witch limits how much lift you can get in a given duration, comp cams has mopar specific cams in witch the lobes would not work with a chevy lifter. The faster higher opening means less duration and that generally means more tq while the higher lift generally translates into more HP, sort of the same reasons roller cams are advantageous and as a matter of fact on very short duration cams a big mopar diameter flat tappet lifter can get the valve open higher and faster than a roller.