fuel flow also reduces power which will also make the plane impossible to get off the ground and you may as well be flying with more tanks.
Basically all the BBJ1 is, is a 737-700 that has strengthened landing gear (MTOW increased to 171,000 as opposed to 154,000) and 9 Auxiliary tanks (adding 3,832 gallons) in the belly of the plane.
Nothing really that different aerodynamics wise

Maybe a few more antennae but thats about it.