Dihadron angular correlations in forward pA collisions have been considered as one of the most sensitive observables to the gluon saturation effects. In general, both parton shower effects and saturation effects are responsible for the back-to-back dihadron angular de-correlations. With the recent progress in the saturation formalism, we can incorporate the parton shower effect by adding the corresponding Sudakov factor in the saturation framework. In this paper, we carry out the first detailed numerical study in this regard, and find a very good agreement with previous RHIC pp and dAu data. This study can help us to establish a baseline in pp collisions which contains little saturation effects, and further make predictions for dihadron angular correlations in pAu collisions, which will allow to search for the signal of parton saturation.