HJS ECE Downpipe 3" for Golf Mk7R and Audi S3 8V

HJS specialises in exhaust emissions technology, offering catalytic converters and downpipes for tuning and motorsport. Its ECE Tuning range includes designs with metal catalyst substrates rated at 200 or 300 cpsi.

These products offer an option for upgrading the front section of an exhaust while retaining a catalytic converter. Check approval coverage for the exact part number and vehicle variant, as not every HJS product has the same intended use.

HJS catalogues distinguish between HF, HD and TS metal-substrate designs. These vary in foil winding and channel profiles, selected for durability or exhaust-cleaning efficiency. Tuning products carry identification details such as a type plate, serial number and HJS marking, helping the buyer identify the exact component.

History and development. HJS was established in 1976 and focused its development on reducing combustion-engine emissions during the 1980s. It pioneered retrofit catalytic converters and helped develop SCRT solutions combining exhaust-treatment technologies. The company celebrated its fiftieth anniversary in June 2026.

The business today. HJS Emission Technology now operates in Menden, developing and manufacturing exhaust-aftertreatment systems and associated mechanical and electrical components. Tuning and motorsport products form part of a broader technology business, serving both performance-car upgrades and wider emissions-reduction applications.