The main objective of this paper is to investigate the performance of partial filtration DPF substrates using 3-D Computational Fluid Dynamics (CFD) methods. Detailed 3-D CFD simulations were performed for real world sizes of DPF inlet and outlet channel geometries. Two concepts of partial filters were studied. The baseline geometry was a standard DPF with the front plugs removed. The second concept was to eliminate half of outlet plugs in addition to the inlet plugs to improve the pressure drop performance. The total filter efficiency was defined in current study to quantify the overall filter filtration efficiency which combines the effects from wall flow efficiency and flow through efficiency. For baseline case, 45% of total exhaust gas was found to go through the inlet channels, and the total trap efficiency was as high as 60%. However, only a 10% pressure loss reduction was found due to the removal of the outlet channel plugs from the DPF inlet side. With the further reduction of the number of inlet channel plugs by 50%, the pressure loss can be reduced from 3kPa to 1.6 kPa while still maintaining a 40% total PM trapping efficiency. The effects of wall permeability, DPF length and total exhaust mass flow were also investigated. Additionally, the percentage of exhaust flow going through inlet channels and total filtration efficiency increase as a function of wall permeability, DPF channel length and total exhaust mass flow rate were studied.