Beyond BS-IV, meeting emission legislation is an exigent target for diesel engine manufactures. But there always exist a compromise between engine performance and emissions. However the development of proper combination of Fuel Injection Equipment (FIE) system along with low cost after-treatment development for Indian vehicle applications to reduce the emissions plays major role to meet the engine target cost. Therefore in this study significance of using K and Ks nozzle is experimentally investigated for its effect on emission performance. In addition to maintain proper NOx/PM trade-off, an increased EGR flow rate along with higher cooling efficiency is improved. This increase in cooling efficiency is made without compromising other requirements in the design of the EGR cooler. The buildup of carbon deposits in EGR coolers causes significant degradation in heat transfer performance, often on the order of 15% - 20%. Deposits also increase pressure drop across coolers and this may degrade engine efficiency under some operating conditions. Hence computational analysis is carried out to select proper combination of corrugated EGR cooler tubes and water mass flow to increase EGR gas heat rejection rate. Further for proper exhaust flow through the DOC substrate to have better emission conversion efficiency with less PGM, substrate volume as well as uniformity index optimization is made. Hence proper combination of FIE, EGR system and conventional after-treatment system can meet BS-IV/V emission norms without any additional advanced after-treatment systems.