Just bought an 07 Sierra VMax with AFM, can you put dual exhaust on and will it sound crappy when engine shifts to 4 cylinder?

 

It will sound great if you put a muffler on it that doesn't give a drone noise. I put a 50 series Flowmaster on mine and when it converts down you can hardly notice that it is even running. If I put an exhaust system that makes it sound louder all the time then yeah it would sound like it's missing.

 

Thanks for your input. I read on another forum that there would be back pressure issues but sounds like its fine on your truck.

 

honestly, dual exhaust isn't going to do anything for you except rob all your bottom end. Not worth it if you ask me. These LS based engines are picky and won't perform good with an old fashioned dual set-up.
Single exhaust done right is going to net you better flow/power curve all around and just as good sound as well, depending on your set-up.