Results from our radiative transfer simulation, verifying that the SN spectrum is not significantly altered by the CSM interaction. This “snapshot” simulation is for a SN Ia at maximum light, with the W7 model of Nomoto et al. (1984) (blue) and a BB component with temperature 6000 K (wine). In the optical wavelengths, their sum (green) is not significantly different than the fully simulated spectrum (black), for the (relatively strong) mass-loss parameters assumed here. The simulations refer to a distance of 10 Mpc.