Vibrant Performance 4-1 Merge Collectors have a single slip design ideal for naturally aspirated applications, featuring precise cut mandrel bent 304 Stainless Steel tubing with high quality TIG welded construction. Vibrant merge collector expanded inlets are designed to fit perfectly with Vibrant Stainless Steel piping. 4-1 Merge collectors range from 1.75? to 2.25? for inlet, and 2.5? to 4? outlet sizes.