The JUN exhaust manifold is compromised of stainless steel SUS304TP and the flange is manufactured by their CNC machining center. The 4-2-1 Manifold is designed to gain the maximum performance through the lightest weight and strength using the same process of developing the racing-use parts. The 45mm ID primaries and 60.5mm collector make for an excellent manifold. Low-end torque is gained in conjunction with a healthier top-end powerband and vtec transition. JUN introduces a completely different exhaust system in comparison to the OEM JDM 4-1 found on the ITR. The JUN 4-2-1 exhaust manifold is designed for the JDM 98 Type-R, however, the primary flange will bolt up to any B-series engine; slight modification is needed at the collectors end.