So you have a downpipe, test pipe, and cat-back exhaust on your EVO and you want more power. If you still have the stock o2 housing, do yourself a favor an upgrade to this high flow invidia unit. The invidia o2 housing flows much better then the stock housing and most aftermarket housings. After installation you will notice a quicker turbo spool and more HP throughout the RPM band.

This o2 housing is approx. 2.9". The other o2 housings such as the megan racing, Authority, and DNP are only approx. 2.3"