  We study CP-conserving rare flavor violating processes in the recently
proposed theory of Maximally Natural Supersymmetry (MNSUSY). MNSUSY is an
unusual supersymmetric (SUSY) extension of the Standard Model (SM) which,
remarkably, is un-tuned at present LHC limits. It employs Scherk-Schwarz
breaking of SUSY by boundary conditions upon compactifying an underlying
5-dimensional (5D) theory down to 4D, and is not well-described by
softly-broken $\mathcal{N}=1$ SUSY, with much different phenomenology than the
Minimal Supersymmetric Standard Model (MSSM) and its variants. The usual
CP-conserving SUSY-flavor problem is automatically solved in MNSUSY due to a
residual almost exact $U(1)_R$ symmetry, naturally heavy and highly degenerate
1st- and 2nd-generation sfermions, and heavy gauginos and Higgsinos. Depending
on the exact implementation of MNSUSY there exist important new sources of
flavor violation involving gauge boson Kaluza-Klein (KK) excitations. The
spatial localization properties of the matter multiplets, in particular the
brane localization of the 3rd generation states, imply KK-parity is broken and
{\it tree-level} contributions to flavor changing neutral currents are present
in general. Nevertheless, we show that simple variants of the basic MNSUSY
model are safe from present flavor constraints arising from kaon and $B$-meson
oscillations, the rare decays $B_{s,d} \to \mu^+ \mu^-$, $\mu \to {\bar e}ee$
and $\mu$-$e$ conversion in nuclei. We also briefly discuss some special
features of the radiative decays $\mu \to e \gamma$ and ${\bar B}\to X_s
\gamma$. Future experiments, especially those concerned with lepton flavor
violation, should see deviations from SM predictions unless one of the MNSUSY
variants with enhanced flavor symmetries is realized.
