Cat Pipe Blues

[OHale]

Good day all,



I bought the DPPI cat replacement pipe and my dealer agreed to install it. After about an hour and a half they gave up: apparently there is a crimp in the exhaust that would require them to cut the muffler flange to 'fit up' the cat replacement pipe. They tried heating the crimp while three mechanics twisted it: no luck. :{



The DPPI product appears to be extremely well made and I can't believe there isn't a way to fit it up without cutting the muffler.



Does anyone have any experience with this and a tip as to the best way to install the DPPI pipe?



Thank you!

 

[Tim]

What is wrong with cutting the pipe forward and back of the cat?

 

[OHale]

Hi,

I went to the other muffler shop myself to talk to the owner directly. Apparently the big problem is the crimp: they don't have a tool that can de-crimp a 4" pipe. They were proposing cutting part of the muffler flange and fabricating and re-welding a transition piece.



I am lost when it comes to exhaust mods. The crimp is a new thing to me. I think they are reluctant to cut an otherwise factory muffler and re-weld. Do I have the wrong shop?



Thanks,

O.

 

[rashwor]

I think it is the wrong shop. There is not a pipe that my muffler guy won't cut and weld. Any way you want it. Money talks and he listens pretty well! :-laf

 

[KevinO]

It's a pretty simple process i had mine off and back on in an hour. I used a dotco cutoff wheel to put a slit in the cat pipe that slips over the down pipe and pry it back a little and it will slip off. then there is a notch at the 12 oclock position that needs to be ground off and the new stuff slips right on and bolts up. The tail pipe needs a slit cut in it too or just cut it off. I saved the cat just in case emissions some day change or dealer doesn't like it off.

 

[OHale]

kevinO,



Thank you, great info! I was afraid to cut the cat pipe in case it wouldn't fit and I had to return it. I was the one that told the mechanics not to modify the cat pipe. After reading your post that makes sense and it dawned on me that it is better to cut a $60 cat pipe than a $$$ muffler or stock exhaust. I do want to be able to put the cat back on.



So am I correct that instead of trying to loosen the crimp from the cat to the muffler you just cut it there?

 

[Tim]

If you slit the pipe, the crimp won't be able to hold the pipe anymore.

 

[OHale]

Thanks, Tim:



I was about to send the cat pipe back but the dealer is going to try to loosen the crimp one last time. They think they can do it.



By the way I live in Maine but the truck is registered in Canada (working there temporarily) so the cat removal is legal. I want to be able to put the cat back on when I return to the US.



I am assuming there won't be much increase in sound level. I do like the quiet truck but as hot as these engines run I don't want any unnecessary back pressure.

 

[KevinO]

When you put the bracket back on and tighten it it will put a crimp and hold it again. The slit just can't be through both pipes just the outside slip over one.

 

[TCDiesel]

When you put the bracket back on and tighten it it will put a crimp and hold it again. The slit just can't be through both pipes just the outside slip over one.

We do this all the time ,Do a slit on the female and remove with air Hammer,Once the female end is removed we crimp it again and weld it again some grinding, and customer can install again with clamp and Re-tighten. We also make 4 slits 1" deep for ease of installation.

 

[nickleinonen]

once you do get it off, get some band clamps... them crimp type clamps are POS

 

[WCPoe]

Ditto on the band clamps

:-laf As nick said. I experienced the same difficultly when installing my MBRP cat back exhaust. I cut slits at several places and finally got the muffler off. Summit has the 4 inch stainless band clamps (w/ 2bolts) for about $8. 34 each, I think. If you use the band clamps rather than the u-bolt the pipe will come off much easier if you decide to change back.

 

[OHale]

We do this all the time ,Do a slit on the female and remove with air Hammer,Once the female end is removed we crimp it again and weld it again some grinding, and customer can install again with clamp and Re-tighten. We also make 4 slits 1" deep for ease of installation.

Thanks TWest and everyone. I am going to print this thread and take it to the shop to let them look it over before trying this.