Mitsubishi Evolution 4-9 4G63 Header Flange AF9551-1019Mitsubishi Evolution 4 9 4G63 Header FlangeCNC Machined with 50mm Port Size AF9551 1019 9551 1019 Custom build your exhaust or turbo manifold with high quality Aeroflow components. Aeroflows CNC header flanges are manufactured from 9. 5mm (3 8) thick mild steel. They are precision cut to meet your ports, reduce warping, and prevent leaks. The Aeroflow header flanges are offered in a variety of header flange sizes and shapes to mate your cylinder heads