i got a 04 2500 HD 4x4 with a 6.0 anyone make a replacement performance muffler for my truck thanks mark

 

Yeah, there should be a lot of manufacturers making replacement mufflers. Magnaflow is a very popular one. Your stock setup should be a dual 2.5" in single 3" out. Correct me someone if I'm wrong.

 

I think that it's dual 2.5's in to dual 2.5's out into a y into a single 3.0 off the muffler

 

its dual in, single out. I believe GMCtrk is 100% right.

 

2.5 in and into a three inch tail pipe. The Y right off the muffler I think is almost like a resonator because if you see a cutout of the muffler it is a single outlet muffler. I think the other outlet resembles the stock intake tube and all the baffles, tubes, and etc off it. Just get a nice Magnaflow or Borla, something straight through that is a dual inlet single outlet. Magnaflows are reversable, Flowmasters aren't. Just keep that in mind.

 

I believe you are correct, the one pipe is for noise cancelling...but there still are 2 pipes coming out of the back of the muffler into a y correct?

 

yes but just a couple inches off the muffler they Y into 1

 

Stock pipes are 2.75" so get a dual 3" in single 3.5" or 4" out with a magnaflow Duramax tailpipe to match. I used an Aero Turbine STX 640 and am happy with the setup, but Magnaflow makes a muffler that would also work. Probably a few other manufacturers as well. Be careful when selecting a tip, I had a rolled tip that resonated badly, but it completely went away when I removed the tip.

 

The HD 2500HD's I have measured are dual 3"(OD), from the manifolds through the cats to the dual in dual out(dummy dual out-only 1 side actually flows exhaust).

I'm pretty sure in an 8.1 engined HD that BOTH outlets of the muffler are used.

Flow Pro also makes some direct fit replacements.

peace
Hog

 

i have a 50 series flomasters for sale, dual in single out, with a turndown welded on. Off my lq4 6.0 denali. Muffler sounds great, deep, nice idle, not loud on highway at all, im just about to be due for inspection (muffler turndown on suv is illegal) and i kind of want to go with a stock muffler and get some cut outs. pm me if your interested.