Universal 4-1 T3 T4 Turbo Flange Mild Steel Header Manifold Merge Collector100% brand new items, never used or installed. Universal mild steel 4 1 header turbo manifold merge collector for T3 T4 flange. Made by OEM approved manufacturers with materials that meets or exceeds strict OEM requirements. Manufactured from high quality mild steel with CNC machined flanges for superior strength and durability. Merge collectors make a cost effective & low effort solution for custom manifold fabricators. Cast with precision modeling,