Well, i had both. So, im going to say this..... The ram air works really good (its designed to) and so does the cai. But, if you run your car with ram air, then swap to cai, odds are that it might give 2-5 more hp, but, when your playing with 250 hp (on average) already, you probably wont see any gains that are mind blowing.
But it does clean up your engine bay.