Forrest - Do you cut the end off the cat, stick in a piece of 4" exhaust tubing, then weld the end back on the cat?

Will it actually mess up the flow if you just leave an empty cat? The cat plugged up on an XJ I had, so I broke up the catalyst and left the chamber empty. It created an empty drone sound in the exhaust. I didn't like the sound.

 

it won't hurt flow as much as a non-gutted cat, but it'll hurt more than a straight pipe or straight through muffler would...

when you get the cat off, you'll see what you need to do... it's tapered at one end, and kinda rounded at the other end... just cut off the tapered section so that a 4" pipe can slide through it... the rounded end will be a little harder, but far from impossible... a 4" hole saw would probably help, but you could probably do it w/ a saw if you hold your tongue just right... but hey, if you can't weld a gap, you're not redneck enough

 

Then weld the 4" tubing to the shell of the cat, and then weld the end back on the cat too, correct?

 

don't weld the end back on the cat... the end necks down to 3" pipe. you want 4" pipe... when you dive under there and look at it, it'll be slef explanitory.

and in reality, the cuts/welds don't have to be perfect if you run the pipe all the way through since the shell won't actually be seeing any exhaust. but the cleaner it looks, the less attention it'll attract from any prying eyes.

just wondering why you're so worried? there's no inspections on diesels in CA

Forrest

 

I'm not worried. I was just asking how you went about piping the cat. It makes sense that a hollow cat would impede the flow, due to the turbulences. I don't mind the 3" pipe anyway. I'm completely stock.

I have a favorite exhaust shop, and am hoping he won't object to removing the cat for me.

 

its a diesel, its perfectly legal to run straightipe. its not really even a cat, they call it a resonator. so your not really even cutting a cat off. its a resonator, and they don't say anything in the books about not allowing a resonator to be cut off. at least thats how it works in texas.

 

well, that's NOT how it works in TX... on a 94-98 12v, there is no resonator... there is a catalytic converter... the 98-03 24v's had no cat, just a round can shaped resonator... it is a federal crime to remove a catalytic converter, and a stuck up inspector who actually knows what he's doing will call it out... and a highway patrol officer who knows what he's doing and had a really bad day could make you have a really bad day if you know what I mean

Forrest <-- straight piped in TX but well aware of the laws

 

ALL 94-98 12V CTD's intended for sale in the US came from the factory with cats. C'mon, where you been banks?