As for the inspection part of your question i cant help much because fortunately Alabama does not require the emissions testing like TN does. If a cop ever sees someone black smoke round here he will probably pull you over just to ask you what tune your running.
If you delete the DPF then you will need to have a programmer as well. This programmer must have DPF off capability. 97 percent of the sound that you hear on straight piped trucks comes from the DPF and CAT being replaced by a pipe. The only difference i noticed in my truck was when i took off the muffler i could hear more of a rumble in the cab (i ran without DPF and CAT for a year before i removed muffler). Keep in mind that if you are trying to "fool" the cops into not thinking your truck is in violation of emissions standards then muffling the sound as much as possible is the way to go. When everything is deleted it is a very distinct sound if you know a lick about diesel trucks.
Like i said before i can not help much on the emissions testing advice because i have lived in Alabama my whole life. However it is safe to say that when you go to get tested, you best have all your emissions equipment on your truck unless you hollow out your DPF and leave just the shell on there.