The CAS unit is not all bad.
You may get one around $250.
CAS service flat out sucks and they still supply the wrong fittings.
Don't use their useless scoop unless you want it to look like those pics.
It bolts in stock placement, but may require some extra washers to get the brackets spaced evenly. Supposedly due to differences in GM manufacturing.
The CAS brackets can be modified so that the Cooler can be "pushed" up higher for better ground clearance.
I'd say in performance it is equal or marginally better than the stocker just b/c it flows more.
If price is driving your decision that's a cheap replacement.
Griffin makes one that can be fitted into the stock brackets, requires cutting.
No idea what fittings it comes with or how it works.
Air/Air is alot more involved, probably $800+ and lots of installation.