Hoping to get some advice here on a new exhaust manifold for my LHD 240Z. It has a tubular exhaust manifold and a Janspeed exhaust system. I believe the manifold is mild steel, judging by the welds that have been previously done. However, it’s leaking in a few places and beyond repair. So I need some advice on the best option for a replacement manifold. Cast Iron, mild steel, stainless? I have been told that stainless manifolds crack easily and that tubular manifolds aren’t really necessary. These questions might be academic if you can’t actually source these things! The car actually has an L28 engine and has been tuned to Stage 2 with a gas flowed cylinder head and high compression ratio (producing around 190BHP).