Originally Posted by zhilton

[The legal crap from my lawyer, Susan Moore with Dewey, Cheatem & Howe]
Doing this mod to your truck is illegal, and I claim no responsibility if you do this to your truck.

With allot of time on my hands lately I've been trying to do some simple mods to my truck; I've wanted to euthanize my kitty for some time now...but I'm not in the position to go with a 4" Turbo back. I had been looking around locally for 3.5" pipe so I could just have a muffler shop delete the cat...no one carries it. I didn't really want to shell out the $75 for a piece from an aftermarket exhaust company. A buddy suggested going to a salvage yard and getting a piece of straight exhaust off a wrecked SD. So a couple of weeks ago I went to one of the local yards looking for PSD powered SD. When I got out in the yard I discovered a '00 extended cab SD that had a straight pipe under the cab where my kitty was on my '04. I paid the man $20 and I came home with the straight pipe you see below:


After comparing the two side-by-side I discovered the one from the '00 is about 6" longer than the one from my '04. If you go to a salvage yard...your looking for a '99-'02 SD with the automatic tranny (4R100?). From what I've been able to figure out from our fellow SD owners in the 7.3L forum...the trucks with manuals had the kitty cat; as well as all the California trucks. The slush-box trucks didn't have the kitty until the 6.0L started to appear.

With the help of a buddy (the pipes are awkward to handle while laying under the truck) we removed the OEM pipe from my truck and bolted the '00 in it's place. Both are the exact ID/OD and the donuts is the same on the engine end. There is a slight difference where the exhaust hangers are. On the muffler end I'm not going to worry about it (there is two hangers within 8" of each other ahead of the muffler) and the one by the do-nut is close enough that the "dog bone" can reach it...just isn't straight up and down like the OEM set-up.



Looking back toward the muffler....



It took us about 2 hours to do all the work which included fighting with getting the pipe out of the muffler; cutting the excess pipe off the '00 and bolting everything together. All the bolts are 15mm, and came off quickly with the help of an air ratchet. I haven't checked my mileage yet to see how much it's come up. But my turbo is noticeable when I "gas on it" and there is a very faint rumble/turbo whistle when the truck is idling. Something to think about if you want to loose the cat but don't have the $$$ to shell out for an a/m system or delete pipe from the a/m guys.

Originally Posted by dukie1877

anyone else have luck with the sound by running a pipe through the cat housing for those of you that just hollowed it out? Mine is hollowed out and welded back in just wondering if I should cut it back out and strait pipe it through the cat.

Originally Posted by mtnxtreme800

I gutted my 7.3 and my 6.0, I thought both sounded better and spooled up quicker, the only difference I noticed was more turbo whistle, no odd resonance on either truck.