Based on recommendations on this board I had a Flowmaster 50 swapped in place of the stock muffler on my 2007 Avalanche. Just the muffler, I did not modify anything else, left the rear stock tailpipe complete with resonator. It sounds almost perfect, nice and quiet inside the truck but just enough sound so I can hear the engine running with a little rumble. I was worried about the dreaded drone but it's fine. My buddy rode up to the river with me while I towed my boat earlier this week, it's about 100 miles. About half way up I asked if he noticed my new muffler, he said no, but it sounds good. I don't run overdrive with the 5000lb boat in tow, at 2500RPMs even pulling the load with moderate acceleration up hills it was completely acceptable. Way better than my buddy who put something else on his Denali. Going down the same road with his boat in tow, it was miserable.

I'm very happy!

 

I had a 50 series on my RCSB and I liked it too. No drone.

 

I love the flowmaster sound. and price too. with that said, I've never had a flowmaster lol.

 

When I bought my truck it had a flow 50 on it. Sounded pretty good and really had no drone to it all. But it didn't take long to rust out. This is back when it was factory stock. Now with all my current mods, the Dynomax 3" stainless catback I installed has a much better sound to it and is also what I would consider drone free.