Ceramic fibers, in a knitted structure, offer an elastic deep-filter medium having a very high specific surface. The robustness of this trap, and its invulnerability to thermo-shock, was demonstrated during a further year of development and tests. By using new manufacturing techniques, the filtration efficiency was further improved, pressure losses reduced, and the required volume diminished. New insight was obtained regarding the employment of the fiber medium for catalysis. The filter concept permits regeneration either electrically or by fuel-additives. The layout versatility facilitates deployment on vehicular and stationary engines, in the pre-turbo position, too.