So i gutted my pre cats on sunday. No problems other then a stray exaust leak that i just tracked down with the help of a friend. One of the 02 sensors was a tad loose, and in the same spot on pass side, the exaust flange wasnt seated all the way between the pipe and the collector. No emmissions codes were thrown, im adjusting to the exaust note, its a tad more ploppy if that makes sense, at idle it has a tad more of a low pulse to it, then before. Truck is running great, and its always nice to pick up a little more torque.

Also patched two tires that had nails in them, so ill be really checking to see how the truck is running tonight. We think we have all the leaks taken care of, but there may still be one very small one on the drivers side cat.

Ill post up instructions on what i did, at a later time, if some ppl are interested.
-Patrick

 

Interested....

 

I would have posted instructions sooner, but had to slip into class before i was late. So that was just to buy me time

I first cut after the Y pipe, and was planning to undo the bolts and the collectors, and just slide the whole assembly out, Then after freeing the 02 sensors by removing two of them and unplugging all of them. It was then that i realized that the cross member that is directly infront of the Y pipe was in the way and i was going to need to make more cuts...

So i unclamped the drivers side cat assy from the cross over, and unbolted the crossover from the support bracket in the center. And made a second cut infront of the Y pipe. Pulled the cats forward out the front of the truck.

Took the heat sheild off them, after trying to just stick a long wrench and screwdriver in there, but wouldnt make the bend i needed it to make. So on the side of the cat there are small groves, we just layed the sawzall in that two outer of the three groves, and cut a window open by taking a cold chiesel and knocking one end of the slits open, and peeled it back. From there, we nocked out all of the fine honeycomb material inside. You know you hit the edges when you see the black steel wool like material top and bottom, and the sides are surrounded in a cotton type material, looks like dryer lint.

Closed the window back up, welded it up, put the heat sheilds back on, spot welded them just to make sure they dont rattle, and put the assy back into the truck. Lined everything up, spot welded the exaust pipes we cut, and bolted the manifolds back up. Finished welding everything, connected 02 sensors. Ready for test run.

Like i said its actually a little too cat back sounding pop, when reved, or coming down in gear etc. I am considering redoing it, by filleting it open, and welding a pipe inside the housing, and not only gutting it, that way i get straight flow through, and still looks stock on the outside wtih the heat sheild on. Dunno we will see if i can even get a pipe welded up right that will work, since i dont have easy access to a pipe bender.

Ive been told that on extended cabs, that you can pull the whole cat assy out, without cutting chit up like I had to. B.c the crossmember is behind the Y pipe, and not infront of it like mine is.
-Patrick

 

awesome sounds good. i'll have to consider that.

 

Hmm.....sounds like it'd be pretty easy to do here, there's a few guys who know how to weld pretty good too Sounds like it'll be pretty easy on my extened cab too...

 

I did that too, before I got my long tubes... I really liked the sound It gave me.

 

Did you gut all the cats or just two of them? I'm thinking about gutting all of them. Any downsides to this?

 

Well with them all gutted, you will probably throw some codes. I Just gutted the front 2. Now I have the long tubes, and 1 magnaflow high flow cat after each header, and no codes at all.

 

I gutted the front 2 and done away with the back ones about 9,000 miles ago.Hasn't throwed any codes.

 

Yeah, some people have been lucky, others get codes by just replacing the factory muffler with a high flow... What ever you do, it will sound good!

 

It's decided then..I'm gutting my cats

 

You will be happy! I used a crow bar, hammer, and a long chissel. I got them both off, gutted, and i was test driving it in about 2 hours. good luck!

 

Did you have to cut open the cats to do it? I'm thinking about just cutting them open and putting in a piece of pipe through it...

 

on the extended cab trucks its easier because of the cross member location u can just unbold the flanges and unscrew the 02 sensors and it should drop down. enough for you to get after it with a screw driver and a hammer. be sure to suck up and blow out any of the dust so that the EGR will not recirculate any of it and also so it doesnt clog up the other 2 cats.

 

Faster I'm gonna bust out all of the cats....