The only CAI that's guaranteed to not trigger a Check Engine Light on the Mazdaspeed6. Replaces the restrictive stock air box and it frees up about 10 hp, plus the cool sounds a turbo car makes hehe.
Pretty easy and straight forward. Hardest part was dealing with the fender splashguard and removing the resonator box. Other than that it was a breeze. Highly recommend to reset the ECU after the install.