I started with a Flowmaster 40 Series two chamber. It droned in the cab just a bit too much for me. I ended up with a Flowmaster 40 Series Delta Flow which is a three chambe muffler. It had an improved in cab drone but didn't sound much different outside the cab. Note my cab has no insulation or carpet which may have helped with the 40 Series. Another note is that I had the exhaust running out the back under the bumper.
Great video by Flowmaster here giving a breakdown of their offerings:
https://www.youtube.com/watch?time_c...&v=QEBdiW4LbI0
I swear you can watch comparative videos on YouTube all day long and it doesn't seem to do much good, you have to hear them in person to to find the sound and sound level you like.