yeah as stated above with the intake port volume.....180's i feel would be the max that the small bore could handle, and thats pushing it....stock 416's are good for the small chamber, but stock they are like 160cc....opening them up and unshrouding the valves as well as installing 1.94's seem to work well, thats what I did. I'm running true flat tops in mine with a .471" lift cam. This seems to work well with my combo, have to be carefull with the cam selection because the small bore can only suck so much into it.