I have ran LTH+F.I. with 12" res in Texas so if he keeps the stock cats he will be fine.
On the question of other exhausts, it is up to you, listen to videos, where in Texas are you? Can always try to hear some in person.

The inspection places I go to just turn on the car and look for codes. That is all

AZ is supper easy. Nothing for the first 5 years just drop your money in the mail for the tags and their happy :) After that it's code scanner and youre done.

Is your only goal maximum noise level or are you concerned with performance gains as well or maybe the sound of the exhaust as opposed to just the noise level? Fats Intentions has some of the best gains and I am sure it'll probably be pretty loud if you go the non-resonator route. Otherwise, bets bet is just to listen to a bunch online or preferably in person to see which one you like.