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-flowing design builds boost earlier; a suitable flange allows you to fit a larger turbocharger than the original, and therefore aim for a different level of power.

Material choice matters just as much as the design. Cast iron withstands heat cycles without cracking and dampens vibrations. Stainless steel is lighter and allows better-flowing designs, but requires properly designed supports: a cantilevered turbocharger will always eventually tear a weld.