As a global company, NGK does utilize numerous sources as they cannot manufacture 100% of the SKUs in house. NGK utilizes a global supply base in order to provide the full coverage program for NGK Ignition Coils.
The key to remember: 100% of the line is tested to meet or exceed OE specs, as well as NGK requirements. NGK only utilizes specific, NGK approved, vendors if a product is sourced externally. These suppliers have been vetted by NGK Global Headquarters for quality and manufacturing capabilities.
Country of origin is not indicative of quality.