Tig welded from WELD ELL 304L 8GA Stainless Steel. Head plate and turbo flange are CNC cut from 1/2" 1018 mild steel. Jig assembled and back purged welded. These turbo manifolds are designed for superior strength and performance. Comes 44mm wastegate flange standard. Option for 38mm MVS flange available. Designed to fit larger style turbo's such as GT42R/S372