No...not RP's....847 castings.....valve is larger than most, 55 degree seat, 95-96% throat....I have no intention of misleading....makes no sense...if I was to purposely inflate or just plain make up numbers the low lift would be better....it is what it is however....but I think the high end makes up for it...heads are designed for a 4.185 bore....actually don't like much larger and will drop in flow if unshrouded too much more....thanks