I've always heard that you can't just put on aftermarket performance parts without a tune. But I never knew why. Wouldnt like a cold air intake still get you colder air? Or wouldnt a bigger exhaust still free up flow? So what does the tune do? And what exactly is it you are tuning? I saw a vid that said it's because the stock tune tries to keep your pwr from increasing no matter what parts you add. Is this true?