Factory Magnum Heads

Does anyone have an idea why on the intake side they put that bump in the port?? Whats that for? Also besides the stud rocker arms would the TBI heads be better than magnum heads as they still have the swirlport also?? From what i've got with this people should keep the heads the same and spend the money to convert magnums to the LA heads if the la's flow better than the magnums anyways. Can you do flow numbers on the TBI swirlports as a comparison?