if you're looking to mod your cruze for performance, I think a good place to start would be getting a K&N intake. As long as parts come with CARB tags you will be able to pass smog with the tags on your car and you will be legal. Intake doesn't do much but it's an easy install, not pricey, and you get to say you put in your first legitimate mod. That being said if you're looking to greatly increase performance and add a noticeable amount of hp, you might need to start looking into some illegal mods as long as you got a loyal shop to give you dirty smogs for the right price. I heard a centrifugal supercharger will have a CARB tag so you can pass smog while adding a good amount of hp that you'll definitely notice but I haven't heard of anybody trying that yet and putting that on a stock cruze will definitely mess your **** up.