  It has been recently argued that realistic models with warped extra
dimensions can have Kaluza-Klein particles accessible at the Large Hadron
Collider if a custodial symmetry, SU(2)_V \times P_{LR}, is used to protect the
T parameter and the coupling of the left-handed bottom quark to the Z gauge
boson. In this article we emphasize that such a symmetry implies that the loop
corrections to both the T parameter and the Z b_L \bar{b}_L coupling are
calculable. In general, these corrections are correlated, can be sizable, and
should be considered to determine the allowed parameter space region in models
with warped extra dimensions and custodial symmetry, including Randall-Sundrum
models with a fundamental Higgs, models of gauge-Higgs unification and
Higgsless models. As an example, we derive the constraints that arise on a
representative model of gauge-Higgs unification from a global fit to the
precision electroweak observables. A scan over the parameter space typically
leads to a lower bound on the Kaluza-Klein excitations of the gauge bosons of
about 2-3 TeV, depending on the configuration. In the fermionic sector one can
have Kaluza-Klein excitations with masses of a few hundred GeV. We present the
constraints on these light fermions from recent Tevatron searches, and explore
interesting discovery channels at the LHC.
