05 LT Headers + Y + Cats

I just bought my Dad's '05 HEMI. I've been reading a lot of the other threads for a while and trying to learn as much as I can before I ask any questions.

Like everyone else, I want some more umph outta the Hemi, and my first thought was a cat-back system, but after looking under the truck at the factory Y-pipe, I knew that isn't going to stay in there for long. It's apparent that Moe's is the go-to for exhaust, so I started looking around at other options. I'd like to pursue LT headers, but need/want to stay DEQ compliant here in Oregon, so I will be keeping cats.

Here is my current plan:
Pacesetter LT Headers - Ceramic Coated $469
MOPAR exhaust Manifold Gaskets $69.99
Pacesetter 3" Offroad Y-pipe $214
Magnaflow high-flow Cat w/02 **** X2 $225.98

It's my hope that the 12" body/16" overall length of the high-flow cats will fit in the length of Y-pipe, AND that by choosing cats that have an O2 **** in them that I won't throw any CEL codes and have to mess around with antifoulers so the system can run as designed.

For those that have done this, will that set-up fit between the stock muffler and the exhaust ports, or am I going to have to do a custom cat-back system at the same time? I want a little more growl, but I really don't want it loud or any drone. I leave early in the mornings for work and I don't want to be obnoxious to my neighbors.

Also, where are you guys getting ARP exhaust manifold studs? ARP's site doesn't list them, and all I have been able to find so far are MOPAR or Dorman studs.

I have the pacesetter headers and y pipe on my 03, I can take some pictures of the underside tommorow if you want, that should give you a idea of the space you have to work with. I removed the cats on mine, didn't want to pay for the new converter and I don't have emissions. I'm gonna say it will be a tight fit especially on the driver side if you have a transfer case. I used stage 8 locking bolt kit from summit, about $60, seemed to do the trick. You probably need o2 sensor exstenions, I think the headers come with some wire if you want to solder your own, or buy some Casper electronics extensions for about $25.

Some pics would be great. And if you have a tape measure handy, could you check to see if there is enough room on each collector side of the Y-pipe to cut in the 16" long cats without increasing the overall length, that would be awesome.

So then I take it that part of the problem with the LT headers and the O2 sensors is that the cats end up being too far back to get hot enough to work properly?

JNemec said:

Some pics would be great. And if you have a tape measure handy, could you check to see if there is enough room on each collector side of the Y-pipe to cut in the 16" long cats without increasing the overall length, that would be awesome.

So then I take it that part of the problem with the LT headers and the O2 sensors is that the cats end up being too far back to get hot enough to work properly?

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Not totally sure how hot they have to be to work. But the original y pipe is a good 20" or so further forward then the new y pipe. The end of the headers extend quite a ways towards the back of the truck so the sensors won't reach behind the cat. They work of for the front sensors, the headers have a **** at the end.

I used oem 6.1 bolts on my longtubes.

Sorry it took so long, I worked all day Saturday. Here are some pics I snapped underneath. As you can see, there is not a lot of room on the driver side if you have 4wd. I'm not sure how effective a cat would be after the y pipe, maybe someone else can chime in.




It runs pretty close to the transfer case

Thank you, I appreciate you taking the time to take those pics. Looks like you are using a anti-fouler straight into the Y-pipe. Any CEL code issues like that?

I would think that in order to make a cat actually function that far back, the Y-pipe would at least need to be ceramic coated as well in order to retain the heat that far back, maybe even wrapped as well.

JNemec said:

Thank you, I appreciate you taking the time to take those pics. Looks like you are using a anti-fouler straight into the Y-pipe. Any CEL code issues like that?

I would think that in order to make a cat actually function that far back, the Y-pipe would at least need to be ceramic coated as well in order to retain the heat that far back, maybe even wrapped as well.

Click to expand...

I didn't have any codes, and my other o2 sensor is just zip tied to the frame. That one seemed hit or miss about throwing a code. But now I have a custom tune and they are turned off, so no problems at all now