I know this shows how stupid I am but I need the info. I want to put a new air intake on my 08 GT 500. Everything I read states that if I do this I also need a custom tune. I can even buy the intake and tune together in a kit. The problem is I am vague on what a custom tune is. I see the little devise in the adds, and obviously it tunes the engine, but could someone expalin in laymans terms what is actually does and what are the steps involved in the process of doing it? Do they come with directions and is this something a novice should attempt?