I'm sure the LT's add to the "sound", but LT's or not, it's the muffler that is predominantly responsible for the noise you end up with out the back.

 

Look around for a chambered muffler, That will give you the sound you want. The flowmasters are a bit loud to my liking. It's a bit of a trade off if you want a growl and still be able hear the radio at highway speeds.

 

How much would two more feet of pipe and tips make after each of these cherrybomb extremes make? Any chance it will get rid of that crackle sound

 

I've got a single in dual out spintech 5000 series. Nice deep sound, no crackle in the cab (some on the outside but mine heads straight out the rear), and I don't have a cat either.