exhaust manifold redesign for turbo application Anyone

hello i hope you doing well, i have an exhaust manifold that im looking to redesign, its a manifold that will be mated to a turbo, i need to keep the same locations for the headers flange and the vband (inlet of turbo) i will need the thickness of the shell to be around 3mm and the part will be 3d printed in 316 stainless steel, im looking to increase flow and reduce weight, the collector pipe size is 2.5inches and i will need that to be changed to 3inches and have a smooth reducer by the turbo vband to accumulate for a smoother air inlet, the main reason for doing that was that im having restriction in air flow , it will have two sides of manifold, im providing scans of both sides, but for now i have only the passenger side and will soon provide the driver side manifold also read less