From Jani Niskanen in Finland we have an 8-valve manifold on a 2.1 l BMW M10 racing motor. Here are his comments:
"Header is made from 316 pipe and curves, without any cracking problems...it's almost equal length, max difference is 15mm.
"My engine (2084cc BMW M10) makes 578hp at 2.2bar boost, on normal 98 octane unleaded fuel. The wastegate is little bit low now, but I'm making a new header to get gate better position, and flow better, too."