DIY (No Weld) Magnaflow 12909 Kit

EricTheRed · August 26, 2020

I decided to cut the exhaust valves and muffler out of my 6.2L Trail Boss and make a 3.5in straight through system that I could clamp together on the driveway at home. I cut at the points where the factory exhaust was 3.5in diameter and used the parts listed below which are all 3.5in diameter too.

Here’s exactly what I used:

1x Magnaflow performance muffler 12909
1x Walker 12in heavy duty connector 41983

1x Walker 6in heavy duty connector 41978

4x Walker lap-joint band clamps 33273

These parts will fit together without any modification and fill the gap perfectly when you overlap the ends a bit. It also allows you to put the muffler as far back or forward as you want since you can rearrange the pieces however you like.

I love the deep rumble sound but be warned there is a small amount of drone at 1500 rpms when going uphill, not enough to bother me. I did notice the truck has better throttle response and runs smoother. The DFM makes a bit more noise than usual but I’m getting the Range device as soon as it’s released and can just run in L9 until then.

I’m not sure about fuel economy yet or where the final muffler placement will be. I just moved the muffler as far back as it’ll go (the middle of the muffler is now directly in line with the gap between the cab and the bed (crew cab short bed).

I hope this helps if anyone was considering the same. See photos for more info.

Edited August 26, 2020 by EricTheRed
Added photos

TRKLGND · August 26, 2020

Great write up. I'd like to ask a few questions.

What was the parts cost?

How much is a Range device?

You said that the DFM make a bit more noise than usual. I have never heard mine. Not once. What does it sound like? I remember hearing AFM but nothing so far with DFM.

econometrics · August 26, 2020

Wow, very nice job on this, EricTheRed! Looks great, and I'm sure it sounds excellent.

204Denali · August 27, 2020

solid write up!

Steve-2019 · August 27, 2020

Very well done!

Spyderwebb · August 28, 2020

Nice, how about a sound clip!

Brett Glover · February 9, 2021

Really appreciate this write up. Very informative. Allowed me to order all the parts and install myself. Love the results, v8 sound without being too loud and no drone or chopper noise. I live in country australia with no exhaust shop, so to be able to do it yourself and love the results is win win.

mrtizzom · April 25, 2022

Here's to reviving an old thread. I did this exact setup this weekend. Went fairly smooth and all went together good. Only hickup I had was the rear cut is super close to the hanger so there isn't much room to get the clamp on. Had to do a little tweaking to get it all lined up but overall went well. I like the sound...not overly loud but can tell there is still something more than stock there. No drone noticed on the way into work this morning. Curious to see how it'll sound pulling the camper. Thanks to the OP for this write-up.