Maybe "drone" isn't the proper word to describe it, it resonated. It wasn't a noise coming from the tailpipe, but the resonant frequency of the exhaust syncing with the resonant frequency of the engine at a certain RPM. Very annoying. My dad also had a magnaflow X muffler like I run on my Lightning on his '04 K2500 HD chevy w/ a 6.0 and it did the same thing to the person in the backseat, it sounded awesome, but drove you nuts from the backseat.

I don't know if it's because the muffler is under the body on a bronco or what, but cruising on the highway I wanted to poke my eardrums out! You could only hear it from the driver's seat too, any other seat was fine, and it was whisper quiet on the outside unless you had it floored you couldn't even tell it wasn't stock. I've never hated an exhaust so much as that one.

I have since used the Thrush welded (flowmaster 40 clones) on 2 exhausts I've done and been very happy, drone was very minimal w/cats.

They are cheap yes, about $30. If you want to pay more money for a flowmaster 40 that's the exact same thing, be my guest!

I'll post a clip when I'm done, I need to take a clip of my Lightning also, at full throttle it sounds so gnarly, like it has 500 HP (Really has about 300)

 

I can't stand chambered mufflers at all. They drone/resonate worse than anything else. I will never buy Flowmaters or similar mufflers again. They drone with and without cats. I have been in many different vehicles with these mufflers and can't stand any of them.

I have heard that sometimes Magnaflow and similar mufflers resonate inside the car. I know that some Vettes have this problem. I have never experienced it though. It must have to do with muffler placement.

I will only buy straight through or turbo mufflers.