Possible those are just the canned tunes.
Depending on the CAI, it may just have a canned tune just for use in correcting the speedometer for the 3.73 gears. Some CAI’s require a custom tune, some don’t.
Your car will not run correctly.
Yes
You shell out the money for a custom tune. You’ll also have to make sure the tuner (outfit/person who writes the tune) you choose works with the tuner (the electronic device) you have. I put long tubes on my Mustang last year. My tuner is a guy that owns a local speed shop, so it was put on the dyno and had a custom tune made for my specific car, which going to yield better results than a canned tune or emailed tune, but at the same time is much more labor intensive and costly.