High flow full 3" O2 housing for Evo 4/5/6/8/9. Deletes the factory donut gaskets to eliminate the 2.5" restriction between most O2 housings and downpipes and creates a true 3" all the way through flow-path from entry to exit.

Works fantastically well with large stock location turbos with large turbine wheels. This eliminates one of the biggest bottlenecks in the Evo exhaust system.

Also, 02 bung is strategically located away from the direct exit of the turbine wheel to avoid additional restriction and turbulence.

Please note that we advise that you use a mating downpipe that has an integrated flex bellow after deleting the donut gasket. This will ensure vibrations and engine movement during driving is properly absorbed to avoid stress damage to other parts of your exhaust system.