you get better gas mileage because there is better combustion of air/fuel mixture in the chamber.
you get gains because better air flow basically, the engine could breath in more with an aftermarket Intake
, and can exhale better with an aftermarket exhaust.
as for the tpr Intake
, whoever is out of california shouldnt worry about CARB. as for the residents of california, if you really worried about the CARB number, then buy a used AEM Intake
, take the CARB sticker off of it, and stick it on the TPR Intake
. simple as that