  The recent birth of gravitational wave astronomy invites a new generation of
precision tests of general relativity. Signatures of black hole (BH) mergers
must be systematically explored in a wide spectrum of modified gravity
theories. Here, we turn to one such theory in which the initial value problem
for BH mergers is well posed, the Einstein-Maxwell-dilaton system. We present
conservative estimates for the merger parameters (final spins, quasinormal
modes) based on techniques that have worked well for ordinary gravity mergers
and utilize information extracted from test particle motion in the final BH
metric. The computation is developed in parallel for the modified gravity BHs
(we specifically focus on the Kaluza-Klein value of the dilaton coupling, for
which analytic BH solutions are known) and ordinary Kerr-Newman BHs. We comment
on the possibility of obtaining final BHs with spins consistent with current
observations.
