The key performance evaluation criteria for any automotive exhaust system are pass-by noise (PBN), exhaust backpressure, durability and reliability, exhaust brake performance, aesthetics (if visible from outside the chassis), cost, weight and safety. Also, with changes in emission norms, emission from Exhaust Aftertreatment Systems (EATS) is one of the crucial parameters while designing the exhaust system. This paper covers a critical problem faced during the Beta Proto Build and Testing phase of exhaust tail pipe assembly. The exhaust tail pipe assembly had loose fitting issues, which can cause problems during the functioning of the truck. Parameters like material of the pipe, length of strap, tightening torque and tolerance of the pipe diameter were considered to resolve the fitment issue. The resolution is done with the help of Design of Experiments (DoE) and Pugh Matrix Analysis based on QDCFSS (Quality, Design, Cost, Feature, Safety and Sustainability). Design for Assembly (DFA) is a critical event, especially at Beta Proto Build and the pre-launch production phase. It has the dependency with design, parts (piece to piece variations- like dimension, material property), method shop floor facilities / resources (workstation – tools / machines), method/practices (variations – plant to plant / location to location) and workforces (training and physical states - like height). In the subject case, torque loosening / variations and difficulty in assembly have been reported from different plants / proto shops globally for the mounting of the exhaust tail pipe of EU6 heavy Trucks. In this context, Multi-Objective Optimization (MOO) is done with reference to DoE and Pugh Matrix evaluation to resolve the validation phase (testing) blocker problem of EU6 global trucks. Also, Quality Tools are used to do Root Cause Analysis (RCA), find Interim Corrective Action (ICA), and come up with different inputs for DoE. The primary objective of this research is to investigate and optimize the factors involved in tail pipe mounting schemes, which consist of tail pipe (GD&T and material), mounting clamp, torquing, and orientation preference. In material selection, Sustainability which is focused on SOC (substance of concern), CO2 reduction and R-Cycle framework, is equally important in decision making. This work indicates that the DoE technique, along with QDCFSS assessment, is very effective in optimizing multiple factors and resolving the problem identified by the proto build and testing team and ensuring follow the project milestone and business continuity.