Abstract: A system and method for the manufacture of a laser-welded cone-shell catalytic converter (100) is provided. An unformed shell blank (111) is formed into a cylindroid shell (110) having overlapping edges (112), which are then resistance welded to produce a shell seam (116). The shell seam (116) is planished to a thickness (120) less than 125 percent of a thickness (119) of the unformed shell blank (111). A ceramic catalytic substrate (130) is wrapped in a ceramic-fiber mounting mat (131) and inserted into the shell (110). Ends (125) of the shell (110) are crimped to form a 1 mm turndown (134). A pair of endcones (140) is assembled, where for each endcone (140) an outer cone (141) is loaded with an endcone insulation (142), and an inner cone (143) is pressed into and spot-welded to the outer cone (141). The endcones (140) are fitted to the shell (110) so as to form an overlap zone (151). The endcones (140) and shell (110) are then laser welded by an Nd:YAG laser (253) in the overlap zone (151).