ABSTRACT Mainly Pass by Noise (PBN), Exhaust Backpressure, Durability & reliability; Exhaust Brake performance, Aesthetic-ness (if visible outside chassis), Cost, Weight and Safety are the key performance evaluation criteria of any Automotive Exhaust System. Introduction of different Exhaust Aftertreatment System /Devices (EATS) call for additional emissions evaluation for Exhaust System from EU4 (or BS-IV) onwards. In Engineering Function (R&D), key focus given on above performance parameters of any design and development or new product introduction (NPI) Process. This paper covers a critical problem faced by downstream function of NPI process and its resolution through design of experiments (DoE). Design for Assembly (DFA) is critical event specially at Pre-launch Production phase. It has the dependency with Design, Parts (Piece to Piece variation- like dimensions, Material properties), Method Shop floor facilities/Resources (Workstation- Tools / Machines), Method /practices (Variation - Plant to plant / Location to location) and workforces (Training and physical states -like height). In Subject case, torque loosening/variation and Difficulty in Assembly has been reported from different plants of globe for mounting of Exhaust Tail pipe of EU6 heavy Trucks. In this context, multi-objective optimization done vide design of experiments (DoE) to resolve production / manufacturing blocker problem of EU6 Global Trucks. Also, Quality Tools are used to do the Root Cause Analysis (RCA), find out Interim Corrective Action (ICA) and come up with different inputs for DoE. The primary objective of this research is to investigate and optimize among the factors and finalize the strategy of Tail pipe mounting scheme which consists of Tail pipe (GD&T and Material), Mounting Clamp, Torquing and Orientation preference. Further, it indicates that DoE technique is also very much effective to optimize multiple factors and resolve Manufacturing/Production problem with standardized guideline from R&D function to ensure business continuity. Keywords: Exhaust, Tail Pipe Mounting, Design for Assembly, Design of Experiments.