HKS Exhaust Manifold - Equal Length Header - With Metal Cat - GR86HKS Super Manifold with Catalyser GT SPEC for GR86 Note: Current ETA Feb 2026 The HKS Super manifold (header) is an equal length 4 2 1 design Manufactured from SUS 304 Stainless Steel The HKS 4 2 1 manifold is equal length and has a HKS Catalyser and features a low density metal catalyst to dramatically reduce exhaust resistance, it has passed Japanese exhaust gas regulations. The manifold produces more power in the torque dip area, and top end power