I am new to the forum, but not new to Chevys. I just purchased a 2007 Silverdo with the 6.0 V8. Just put a new exhaust on it, nothing fancy. I have noticed that when AFM (goes to 4 cyl mode) kicks in, the exhaust noise sounds like garbage. Really is annoying. Has anyone else had this experience. Sorry if this is a repeat post. Thanks!

 

Well, its because you have 4 cylinders firing. Most 4 cylinder engines will sound like crap through a 3" exhaust.

 

Better question, does anyone know how to keep it from going AFM (ie keep it 8 cyl) all the time? Does an ECU reprogrammer like from superchips do this?