Originally Posted by adulbrich
Yes, higher motor force equals higher rise.
There are ways to combat the rise on powerful motors, but they are not common with the SPL crowd and they come with some compromises.
Thwarting back-emf by means of a pole sleeve or ferrofluid can drastically reduce the impedance peak. The compromise with the pole sleeve is a loss in motor force, and the compromise with ferrofluid is that it is not conducive to high excursion drivers and needs a lot of motor venting to be stable. However, in addition to the back-emf control of both of those options another benefit is they both help with cooling.
Alumapro Alchemy and the old school PPI pro flat piston subs are two that I can think of which come stock with ferrofluid in the gap and their impedance curves are shockingly flat right out of the box.