This paper presents a focused lean improvement case on a two‑operator seatbelt sub‑assembly cell at a North American Tier‑1 automotive supplier, producing above its designed combined cycle time (actual ~32.2 sec vs. designed 30.3 sec). Hidden losses were identified in motion, layout, and sequencing rather than machine performance. A structured improvement approach combined Value Stream Mapping (VSM), Modular Arrangement of Predetermined Time Standards (MODAPTS) motion coding, Yamazumi load analysis, and low‑cost physical rearrangement. Baseline MODAPTS breakdown revealed avoidable walking, redundant reaches, one‑handed idle, and a micro‑wait at a shared press between the two workstations representing on average 3-6 theoretical seconds of recoverable time per cycle. Targeted countermeasures such as point‑of‑use material repositioning, two‑hand synchronous picking, workload balancing, press control relocation and standardized micro‑sequence delivered a 13.2% cycle time reduction, lifted balance efficiency to 99.6%, and reduced lead time by over 21.9%, all without capital automation. A disciplined combination of micro-motion analysis and lean flow tools is shown to significantly enhance manual assembly performance. This case demonstrates that targeted method and layout refinements are sufficient to unlock latent capacity, enabling the system to exceed its initial design specifications.