For most applications, not all, cold air intakes are the best intakes as far as power, but most of it is the placebo affect. IE you hear the intake so you THINK its faster...
it is bolt on power. not much, but worth it if you plan on doing other things. i ordered a new one today for my truck, a volant. if that is the only thing you are doing to your car i would save my money, but i have much bigger plans for my truck that i am hopefully going to carry out before the year is over though.