Magnafow 12909 muffler install, review, and parts for sale now.

[MNorby]

On my last truck (2008 GMC 2500 6.0) and this truck (2015 Chevrolet 2500 6.0) I kinda always wanted to remove the monster factory muffler and give the truck a little tone. I read some feedback and ended up with a Magnaflow 12909 3.5" muffler. After receiving I noticed the offset isn't the same as the factory muffler and wouldn't be a direct install unless you don't mind the muffler sitting in the truck at and angle to meet up to the existing exhaust. What I did notice was the factory pipe from the flange just in front of the muffler dropped down a few inches and if that were a straight section it would make the muffler offset perfect to reach the tailpipe section. I cut the pip as close to the rear of the factory muffler and unbolted the flange. I cut the welds on the factory ball flange and the hangers to make a new intermediate pipe that will be straight. I picked up a length of 3.5" exhaust pipe from a local exhaust shop and mocked up the muffler and flange and built the new pipe. With this pipe the muffler, intermediate pipe, and tailpipe were all level with the truck. 

 

With it  all installed time to try it out. At idle the truck sounded great, not really any louder that stock but a deep rumble sound. Where I started to question it was driving, I would get a drone around 1600-1700 rpm that wasn't terribly loud but enough I noticed I turned the radio up a little more than normal. Above that and north of 2000 rpm it was fairly quiet in the cab and sounded great. A friend listened outside and said it wasn't obnoxiously loud but you could tell it wasn't stock and had a great deep tone to it. I tried it for a week and finally decided the drone area, especially when towing my rock crawler, was just more than I wanted to listen too on long trips so finally just put the factory muffler back in. No one else in the 2500/3500 section really mentions drone with the muffler but I did find a guy with a 1500 6.2 truck that tried and and removed because of drone. Maybe it has to do with my blackbear tune and something going on in that range differently that the others guys here. I had to grab another factory intermediate pipe since I had cut mine up for the flanges and hangers. 

 

A buddy bought the magnaflow muffler for his ram 2500 6.4 truck but I have this straight intermediate pipe left over I thought I would sell to someone else that might want to try a different muffler with a cleaner install. Pipe is 36.5" long from face of flange to end of pipe and you can see in the last pictures where the weld was and how much fit inside the muffler. PM me if you are interested. 

 

And now for the pictures:

The factory intermediate pipe with the drop down near the flange:

 

Cut the flange and hangers off the factory pipe:

 

Muffler and new intermediate pipe:

 

New muffler installed:

 

Leftover intermediate pipe for sale after cutting muffler off:

 

 

 

Edited August 15, 2018 by MNorby

[SierraHD17]

My Borla drones at that 1700 to 1800 rpm range and used to be quite noticeable on the highway to the point I wanted the stocker back on.  Putting a set of gears in the truck and making my cruise speed now in the 2000 and up rpm range rectified that... and the mileage increased too lol.

Edited August 15, 2018 by SierraHD17