Catalytic hydrogenation of unsaturated molecular precursors with parahydrogen provides a major signal enhancement in NMR, which is vital for many technical as well as biomedical applications. We show that dilution of catalytically active Pd with a less active metal in heterogeneous Pd-based catalysts provides significantly larger enhancements and that the judicious choice of the dilution metal can further improve the performance, as revealed by comparing Pd-Ag and Pd-In bimetallic catalysts.