If you remove the cats or hollow them out, it will definitely trip the check engine light.
To get more sound you can try the following:
Replace cats with hi-flow cats (possibly a larger diameter than stock)
Upsize Exhaust Piping
I'm not sure how restrictive the stock cats are on the 3rd gen Ram. It's different for every vehicle. Chances are you will here a difference in sound but not a noticeable hp increase. A good set of headers in combination with hi-flow cats will give you a good hp and sound level increase.
My advice is watch YouTube videos where people post there exhaust clips and copy their setup if you like it. Make sure you are listening to 3rd gen hemi rams and not 5.9s.
Btw, you might try posting in the 5.7 hemi exhaust disscussion section
. This section is for 5.9L.