you can measure all you want, the fact remains true. you could have two oval ports in the same bore with a bridge. the shape of the oval port makes for a wider power band. as in smooth through the power curve not more power, more smooth. i'd take a sold molded 56er bridge port block, aka fishinmotor. a bunch of dudes got sucked in on that concealed prop, payed big bucks for a copy, they never went as fast. careful about what you think you know....