The modman manifold almost seems to be a gimmick ... it has interchangeable tops so that different carb combinations can be run using the same manifold base but changing the carb mounting plate. Kind of like being "a jack of all trades but a master of none" !!

Consider what the difference of the two manifolds is ... the dual plane will give you more bottom end torque while the single will give you more top end horsepower. On the street, which do you really need ??? A ton of bottom end grunt will let you run less gear - which in turn is more highway friendly.