AUSSIE DE CAT DOWNPIPE CELICA GT4 ST205 3SGTE 3" Exhaust High Flow Downpipe to replace cast elbow and cat, Accepts standard oxygen sensor, With 2 optional bungs for other sensors. This downpipe comes complete with the fitting kit as shown. There is an adaptor ring included which allows fitment to a standard front pipe or aftermarket systems up to 3". High Performance Coated in silver. This downpipe vastly improves exhaust gas flow from the turbo, reducing spool up time, it also provides a smooth and direct path for wastegate gasses, which further improves gas flow once the wastegate opens.