The Belousov-Zhabotinsky (BZ) reaction is the prototype oscillatory chemical reaction.  A typical reaction includes the autocatalytic species bromous acid, an inhibitory species Br^-, a catalyst (here ferroin/ferriin (Fe(phen)₃^+2/+3) or Mn^+2/+3), H⁺, malonic acid (MA) and its halogenated form.  Catalytic oxidation of MA provides free energy to drive oscillations and a source of Br^- on a slow time scale.  Typical reagent mixtures demonstrate either large amplitude limit-cycle oscillations or excitable behavior (an equilibrium state which can be driven far from equilibrium by a suitable small perturbation such before returning to equilibrium), depending upon initial concentrations.  Showalter and Noyes found that the certain BZ reactions displayed oscillatory behavior when initial concentrations satisfied [H⁺][Br^-] < 0.045 M² .  We show from experiment and simulations that steady states (stable or unstable) scale universality with Showalter-Noyes limit, and modified limits characterizes the boundary in ferroin and Mn catalyzed reactions.  Partially supported by NSF CHE-0515691.