The airbox is from Moonlight Fabrication and it's an off-the-shelf item iirc, about AUD$950 with a filter.
Moonlight Stainless 4WD Performance
Home to high quality stainless steel 4WD performance products. Every line, every component, every product; designed and fabricated to exacting measures for the perfect sound, feel, and look.moonlight4wd.com.au
thats bad ass!!!!