Turbo manifold for BMW 1 Series E82, E88, 3 Series E90-E93, Z4 E89 — TA Technix

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. An unrestricted design builds boost earlier; a suitable flange allows you to fit a larger turbocharger than the original and therefore target a different power level.

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