Invidia Catless Down Pipe suit Subaru WRX STI MY01-07.. (Due to all Subaru WRX STI from 01-07 being different down pipes you may need to lengthen the Cat back to fit.. 
The Invidia Downpipe features a Open Mouth Bellmouth. Designed in Australia
Invidia's all new Australian Spec downpipe is a great way to start getting performance HP and Torque.
The Invidia downpipe is constructed of 304 stainless steel tubing to ensure longevity while enhancing power by freeing exhaust flow. 3" mandrel bent piping will bolt up to any stock replacement catback or stock unit.
And the Australian Designed Stainless Cast Head ensures perfect flow.. This is the most advanced Down pipe on the planet for flow and fitment.
And only in Australia, Invidia is covered by the Limited Life Time Warranty.
No Steering Knuckle is required with the Aus Spec Down Pipe