  We discuss the possibility of performing precise tests of $\mu/e$
universality in $B \to\pi \ell^+\ell^-$ decays. We show that in wide regions of
the dilepton invariant mass spectrum the ratio between muonic and electronic
decay widths can be predicted with high accuracy, both within and beyond the
Standard Model. We present numerical expressions which can be used to extract
precise information on short-distance dynamics if a deviation from universality
is observed in the data.
