Left: uNi index measurements of SN1991T-like and Shallow Silicon-like SNe Ia compared with EW(Si II λ6355). The SN1991T-like SNe are disconnected from the remaining sample. Right: distribution of U_SNf − V_SNf for spectra within 6 days of light curve peak. The figure shows data with (orange) and without (blue) reddening correction, where the linear evolution with phase was removed for each (returning distributions with zero mean). The Shallow Silicon (SS) subset of the dereddened U_SNf − V_SNf distribution is shown by the cross-hatched histogram.