6.0 & 8.1 Stock Muffler

[Dr Norm]

Was looking for opinions regarding the factory mufflers on these engines. I've spent a considerable amount of time & money trying to find a good aftermarket muffler for my 6.0 HD, but can't seem to find anything that doesn't "drone" below 2000 rpm. I'm just about convinced to put the stock system back on. Any thoughts, good or bad, about GM's muffler? Also, are the mufflers the same for the 6.0 & 8.1? Thanks.

[Professor]

I understand. I went through part of that myself. Mine is a 99 2500 6.0. I put on a Flowmaster catback and was very unhappy with it. I took it off and put on a Muffler and tailpipe assembly from a 03 2500 HD that had a 8.1. I believe you had the same factory muffler that I did. Mine was a 2 in 1 out. The 8.1 HD muffler is a 2 in 2 out. It then has a 2-1 pipe leading into the single 3.5 inch tailpipe.

My biggest issue was loss in low end torque. It was better from 4000-5500, but it killed it from 1000 to 3500! I didn't seem to have a drone but it was louder. I didn't tow with it so who knows.

I can fix you the flowmaster set up if you want to give it a shot. I don't recommend it though.

[Dr Norm]

Professor,
Thanks for the offer. My HD is an 03, I finally had the stock muffler & tailpipe assembly put back on. It has just as much getup & go but is now quiet. Guess I learned an expensive lesson. Regards.

[a5150nut]

Take a look at the Allied Muffler. Supposed to be same as in Banks Diesel kit. redussed my 6.5 from 4lbs back pressure to <3/4lb. And it IS QUIET!