zippyboy
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So I picked up this 2004 Yukon Denali about amonth ago.
I really like the truck so far, but I been debating on doing an exhaust system on it. I decided to just go ahead and bite the bullet. As a back story, I helped a buddy who has a Sierra 2500 HD setup a system with a Magnaflow bullet and it sounded good so I was leaning towards that route. I have a Dodge already with a flowmaster and did not want both trucks to sound the same. I decided to go with a bullet muffler and chose a Dynomax for a few reasons. 1. I've used their bullets before in the past and they served me well. 2. After viewing multiple brands of bullet style mufflers they all look identical, meaning they probably come off the same assembly line somewhere. 3. Cost was cheaper for Dynomax over Magnaflow. With no logo'd box and holding both in your hands you would not be able to tell the difference. For those wanting to go even cheaper, Summit carries their brand of bullet and the only difference is it is a louvered core (think block cheese grater) where the above mentioned are perforated core (think kitchen paasta strainer). I feel this is a negligible difference in sound/performance but still a difference none the less. The reason I mentioned the Sierra above is the engine is the same, a 6.0, and as it turns out the sierra exhaust were identical once you crawl under the truck. So, this applies to multiple vehicles on the longer chassis, I assume Suburban, Yukon XL, and Sierra/Silverado (possibly only the HD models). So, the objective here is to replace the stock muffler with a bullet......this will be slightly more difficult then a cutout
and replace but we'll get to that.
So the stock system consists of cast manifolds, two cats (one on each side), two disconnects approx. under the passenger seat area, two pipes going into a muffler, two pipes coming out of the muffler, then into a Y pipe, and out to a single tailpipe and tip. Here is the stock setup: Starting from the engine, this is where the two pipes meet and run side by side. This is directly
in front of the disconnect. So for discussion, this is the very beginning on the system as far as we are concerned.
Just beyond that are the disconnects. Spray them with wd40 while you are poking around under there. One is a ball and socket type connection with a flange on both sides. Two nuts disonnects this. The other is a slip fit that has a clamp on it. One nut for this one and whouldn't ya know they faced it up and put a tack weld on it. A 15mm ratcheting wrench works well here.
First thing we have to do is get this pipe down to a manageable size and off the truck. There are a few simple steps to make this happen. One, the hanger just to the rear of the muffler should
be cut off the pipe. We want to salvage it, so cut just up from the weld. You will still have enough rod left to weld it to your new setup. Here's how you would cut it: Keep as much of the rod
as possible.
Our rear is cut. We need to make one cut with a sawzall just after the stock Y merge. You need a single rear tailpipe connection so you'll cut as far up to the Y merge as possible.
Here is is cut. It will gape open because the weight and unbalance of the tailpipe will make it move around. From there back there is only one hanger.
our rear is cut. We need to make one cut with a sawzall just after the stock Y merge. You need a single rear tailpipe connection so you'll cut as far up to the Y merge as possible.
Here is is cut. It will gape open because the weight and unbalance of the tailpipe will make it move around. From there back there is only one hanger.
This is a general idea of what we are going to end up with. The Magnaflow Y pipe will pull us down to one outlet, then we will go into our muffler then out to our stock tailpipe. Because the stock Y merge was actually on the upward slant going over the rear end, we will need to get an upward bend after the muffler.
Factoring in a little bit of room at the backend for our bend, we want to subtract these two figures, and cut the stock pipe somewhere in that vicinty. Well, this ends up working out well because it is just behind our front hanger. Which means it serves as a good marker for reference, and we will end up reusing it exactly as the factory intended. The Xs mark where I'm going to cut, its an estimate and we will make up our distance on the rear side.
Now, before you make your cut, you will want to affix your twin pipes together. The reason is the muffler is the only thing holding their correct orientation. Once you remove it, they will fall apart. By affixing them together ahead of time, they will reinstall exact as they were designed to stock. Here I've inserted some scrap metal pieces along the center of the two pipes. After my cut, they stay put.
This next step is where you will need your welder. The stock pipes are approx 2 3/4". The Y merge is 3 in, 3 out. You need to adapt these. What I did for simplicity was make small lengthwise cuts (about 1 inch) around the perimeter of the larger two pipes, then hammered them down around the stock pipe. This is a very quick and effective way to adapt the two sizes and will reduce the gap between the pipes to a manageable level that you can fill in with a MIG welder. So after you've done that, you should have this....I left the stock muffler there so you can get a visual comparison.
I really like the truck so far, but I been debating on doing an exhaust system on it. I decided to just go ahead and bite the bullet. As a back story, I helped a buddy who has a Sierra 2500 HD setup a system with a Magnaflow bullet and it sounded good so I was leaning towards that route. I have a Dodge already with a flowmaster and did not want both trucks to sound the same. I decided to go with a bullet muffler and chose a Dynomax for a few reasons. 1. I've used their bullets before in the past and they served me well. 2. After viewing multiple brands of bullet style mufflers they all look identical, meaning they probably come off the same assembly line somewhere. 3. Cost was cheaper for Dynomax over Magnaflow. With no logo'd box and holding both in your hands you would not be able to tell the difference. For those wanting to go even cheaper, Summit carries their brand of bullet and the only difference is it is a louvered core (think block cheese grater) where the above mentioned are perforated core (think kitchen paasta strainer). I feel this is a negligible difference in sound/performance but still a difference none the less. The reason I mentioned the Sierra above is the engine is the same, a 6.0, and as it turns out the sierra exhaust were identical once you crawl under the truck. So, this applies to multiple vehicles on the longer chassis, I assume Suburban, Yukon XL, and Sierra/Silverado (possibly only the HD models). So, the objective here is to replace the stock muffler with a bullet......this will be slightly more difficult then a cutout
and replace but we'll get to that.
So the stock system consists of cast manifolds, two cats (one on each side), two disconnects approx. under the passenger seat area, two pipes going into a muffler, two pipes coming out of the muffler, then into a Y pipe, and out to a single tailpipe and tip. Here is the stock setup: Starting from the engine, this is where the two pipes meet and run side by side. This is directly
in front of the disconnect. So for discussion, this is the very beginning on the system as far as we are concerned.
Just beyond that are the disconnects. Spray them with wd40 while you are poking around under there. One is a ball and socket type connection with a flange on both sides. Two nuts disonnects this. The other is a slip fit that has a clamp on it. One nut for this one and whouldn't ya know they faced it up and put a tack weld on it. A 15mm ratcheting wrench works well here.
First thing we have to do is get this pipe down to a manageable size and off the truck. There are a few simple steps to make this happen. One, the hanger just to the rear of the muffler should
be cut off the pipe. We want to salvage it, so cut just up from the weld. You will still have enough rod left to weld it to your new setup. Here's how you would cut it: Keep as much of the rod
as possible.
Our rear is cut. We need to make one cut with a sawzall just after the stock Y merge. You need a single rear tailpipe connection so you'll cut as far up to the Y merge as possible.
Here is is cut. It will gape open because the weight and unbalance of the tailpipe will make it move around. From there back there is only one hanger.
our rear is cut. We need to make one cut with a sawzall just after the stock Y merge. You need a single rear tailpipe connection so you'll cut as far up to the Y merge as possible.
Here is is cut. It will gape open because the weight and unbalance of the tailpipe will make it move around. From there back there is only one hanger.
This is a general idea of what we are going to end up with. The Magnaflow Y pipe will pull us down to one outlet, then we will go into our muffler then out to our stock tailpipe. Because the stock Y merge was actually on the upward slant going over the rear end, we will need to get an upward bend after the muffler.
Factoring in a little bit of room at the backend for our bend, we want to subtract these two figures, and cut the stock pipe somewhere in that vicinty. Well, this ends up working out well because it is just behind our front hanger. Which means it serves as a good marker for reference, and we will end up reusing it exactly as the factory intended. The Xs mark where I'm going to cut, its an estimate and we will make up our distance on the rear side.
Now, before you make your cut, you will want to affix your twin pipes together. The reason is the muffler is the only thing holding their correct orientation. Once you remove it, they will fall apart. By affixing them together ahead of time, they will reinstall exact as they were designed to stock. Here I've inserted some scrap metal pieces along the center of the two pipes. After my cut, they stay put.
This next step is where you will need your welder. The stock pipes are approx 2 3/4". The Y merge is 3 in, 3 out. You need to adapt these. What I did for simplicity was make small lengthwise cuts (about 1 inch) around the perimeter of the larger two pipes, then hammered them down around the stock pipe. This is a very quick and effective way to adapt the two sizes and will reduce the gap between the pipes to a manageable level that you can fill in with a MIG welder. So after you've done that, you should have this....I left the stock muffler there so you can get a visual comparison.
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