Yup they are right on. C&L developed it so if you don't want to get the tuner you can use that insert piece and not throw codes but to utilize the full potential of the intake you'd have to remove the piece and get the tuner.
I'm running one of those. It gives you a noticeable increase in power and I've never had a light come on. I'm sure it would be a lot better with a Preditor or SCT, but every time I get ready to buy one something comes up and I haven't had a chance. If you can't afford a tuner right now, it's still worth putting it on. It only takes a few minutes and I think you'll like it.