Texas laws and federal laws are quite different. Federal law says you may not 'delete' the catalytic converter(s). State laws in texas even vary by county. There may not even be a visual inspection required depending on your county.
Sound ordinances are usually town or township based and are rarely enforced. You really have to look or act obnoxious to get a ticket for loud exhaust in most towns. So the sound you choose be can and should be what you like.
As far as what exhaust you pick, you can spend very little or you can spend a lot. The better exhaust kits will be mandrel bent piping and allow your engine to breath better and free up anywhere from 10-50 hp. It all depends on how much hp the motor is to start with. The muffler you choose has much less affect on the performance than the pipes do. Local shops and cheap online sources use compression bent piping that flow poorly. Again, it's all about your situation, your budget, your driving habits etc.
I'd like you to take a look at this exhaust system as an option for your Duster.
