1997 K2500 GMC 7.4L

[Spareparts]

Hi. So been lurking for a long time and i finally have a question or rant i dunno.
Anyway My local muffler shop in Sandpoint does not want to remove the cats and put duel exhaust on it so i guess ill need to do it myself but i can't seem to find much to accomplish this that is DIY friendly.
I have the dual exhaust with two cats that rattle all the time back to a big muffler into a single exhaust pipe and im pretty tired of the rattle it's also all old and rusty probably about ready to fall apart.
Been that way over a year now and time to get it fixed.
Each pipe has a 02 sensor before the cat's none after so no cats no problem i believe.
I used to know how to weld, but the last time was 25 years ago. I could pick up a cheap Harbor freight welder but don't really want to as i'll probably never use it again.
I guess i would be ok with the same setup but without the cat's. Looking for something with a decent low rumble. Nothing like glasspacs please. I also almost never see anything over 4k rpm's.
Does anyone have some suggestions on anything available? Can anyone recommend a shop in CDA or Post Falls that might be willing to do the job?
Thanks guy's you have the experience and i really appreciate the help.

 

[df2x4]

Not sure how things are in your area but where I am you're not likely to find a shop that's willing to remove any emissions equipment unless they know you pretty well, and even then maybe not. Especially with how the EPA has been cracking down on businesses. Also being a '97 I believe you should have post-cat O2 sensors, although I'm not very familiar with the 454 trucks. If that's the case you'd need to either have them disabled in the tune or fool them somehow to avoid a check engine light after removing the cats.

That said, you can check sites like Summit Racing or Jegs to see what's available regarding DIY cat-back kits. I'm not sure if anyone sells an "off-road" Y-pipe without cats for your truck but I've heard them mentioned here for certain applications. You might check some manufacturer's websites too like Magnaflow, Gibson, Flowmaster etc. They might have better fitment guides than Summit or Jegs.

Welcome to the site!

 

[454cid]

....Also being a '97 I believe you should have post-cat O2 sensors...

GM dropped the second set of O2 sensors for 2000, from what I've been told. I do believe a 97 should have them. My 99 does.

It's not like you can't get new cats. You can get universals that a shop could weld in place, but there is also ready made pipes/cats that could be installed to... pricey, but not as bad as some vehicles, from what I've seen online. I still have my original exhaust, with leaks, but no rattles.

 

[Spareparts]

Ya know i thought it was odd there are no after cat 02 sensors but i have looked and looked and i can not find any loose plugs any place i have no CEL no place for the extra 02 sensors to screw into. So i dunno.

 

[454cid]

Ya know i thought it was odd there are no after cat 02 sensors but i have looked and looked and i can not find any loose plugs any place i have no CEL no place for the extra 02 sensors to screw into. So i dunno.

Rockauto shows both upstrean and down stream O2's for 97..... but they show that for 2000, too.

They don't affect the way the truck runs, it's more to verify the cats are working. I'd still think they would throw a code, Though. Have you had the truck since new? Maybe a previous owner removed them, and had them tuned out in the PCM?

 

[Spareparts]

Bought it used so being tuned out is a possibility.

 

[Schurkey]

I have a '97 K2500 7.4L.

There's four O2 sensors, two in front and two behind the cats.

The OEM muffler is a restrictive disaster. Most guys install two separate mufflers, side-by-side, and two tailpipes. I bought a Treasure Yard OEM stainless-steel muffler with a single outlet, and used the tailpipe that was welded to it. It came off of an older GMT400 vehicle. The tailpipe hangers slid right into the mounting brackets on my truck!

I did have to add a Y-pipe behind the cats, to get the two cats to feed into the single-inlet muffler.

 

[454cid]

I have a '97 K2500 7.4L.

There's four O2 sensors, two in front and two behind the cats.

The OEM muffler is a restrictive disaster. Most guys install two separate mufflers, side-by-side, and two tailpipes. I bought a Treasure Yard OEM stainless-steel muffler with a single outlet, and used the tailpipe that was welded to it. It came off of an older GMT400 vehicle. The tailpipe hangers slid right into the mounting brackets on my truck!

I did have to add a Y-pipe behind the cats, to get the two cats to feed into the single-inlet muffler.

Was the other truck a diesel?

 

[Spareparts]

For anyone interested here is a pic of my configuration. It says 5.7 but mine is exact same setup just a 7.4L
Someone must have removed the rear 02 sensors and tuned them out as i know for a fact the CEL works. When i read it using the Torque app it has no codes.
When i bought it a couple of years ago if i remember correctly it was originally sold in Omak WA and not being a California emission truck led me to think they were never there.
Anyway it is what it is now and a prime candidate for redneck exhaust system fckery
Looks like im going to measure the pipe, order a bunch of wrong size stuff, buy a welder that probably does not work that well and make several trips to the parts store for adaptors but ill get it done.

 

[smokymtn65]

Mine has four but someone removed the cats before I got it. Then they removed the muffle and necked down into a 2.5 cherry bomb about 6in long .. I have not changed it yet but is have 3in pipe to build a dual 3in in to slip over the factory 2.75, and a 3.5in single out to go in a 3.5 single Magnaflow. Then I have a 3.5in single tailpipe to put on it. just need time to do it now.