The turbo manifold supports the turbine and withstands temperatures of up to 900 °C: it is the most heavily stressed part of a turbocharged engine. A clear flow path builds boost earlier; a suitable flange allows you to install a larger turbine than the original, and therefore target a different power level.

The choice of material matters just as much as the layout. Cast iron withstands heat cycles without cracking and dampens vibrations. Stainless steel is lighter and allows better layouts, but requires carefully designed supports: a cantilevered turbine will eventually cause a weld to split.