While type Ia supernovae (SNe) have been used as precise cosmological distance indicators, their progenitor systems remain unresolved. One key question is whether an exploding white dwarf has a non-degenerate companions star at the time of the explosion. In this talk, I will show possible observational features and signatures resulting from the impact of the expanding SN ejecta with such a companion star around the maximum phase and thereafter. Despite a large asymmetry in the ejecta, the predicted diversity in observational features due to different viewing directions (spectra, light curves) is generally within the current observational scatters. The model does predict correlations between some observables, which can be potentially used to constrain such a progenitor path by using up-coming and well-calibrated SN Ia data.