Increase Horsepower and Torque. The Roush Performance Mustang Cold Air Intake kit replaces your stock GT Mustangs restrictive factory air box and paper filter with a high flow filter assembly and intake tube for an increase in horsepower and torque while improving throttle response and fuel mileage. No Tune Required. Unlike other Cold Air Intakes on the market for the 2005-2009 GT Mustangs the Roush CAI does not require a computer re-tune. The engineers at Roush Performance really did their homework to improve your pony's power using the factory tune. Reusable Filter. Roush designed the high flow air filter to be reusable. So no need to go out and buy a new filter every few thousand miles. Just clean the filter, re-oil it, save money, and go! Superior Quality. Roush manufactures the airbox tray and tube in this CAI kit from high quality thermoplastic materials for superior structural stability, and durability. And the kit comes complete with a custom high-flow ROUSH air filter with clamp, MAF tube, Airbox tray with installed EPDM foam hood seal, and the necessary Mounting hardware.CARB Certified for 2005-2006 Only. This Roush Performance Cold Air Intake is CARB certified for years 2005-2006 only, therefore it is only legal for use in California or other states adopting California emission standards for 2005-2006. EO# D-418-14 for 2005-2006 only.Application. This Roush Performance Cold Air Intake is specifically designed for the 2005 to 2009 GT Mustangs and does not require a new computer tune.