4" Factory Cat Mod
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From: Western NC Mountains
4" Factory Cat Mod
Hi Guys,
I recently installed a Magnaflow 4" Turbo Back and wanted to keep the factory cat for various reasons (no dealer hassle, being a little green, etc).
The cat adapters that came with the Magnaflow system were 4" adapters necked down to 3.5 (3.25?) fittings for the factory cat. This made no sense to me, why have a 4" system with a 3.5/3.25 bottleneck. Since the Magnaflow also came with a true 4" cat bypass I decided to use that and weld in the factory cat. The factory cat has flared ends going in and out of the cat section so I measured and cut right where the 4" Magnaflow pipe would slip inside the factory cat on the entry. I used the included Magnaflow 9" section with 2 flared ends on the outlet of the cat so I would have smooth airflow. This also eliminated one more connection point and one less clamp.
Turned out pretty well, just please don't give me a hard time about my welds, I am used to TIG welding aluminum and rarely do stainless :-)
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From: Western NC Mountains
Can't tell any difference in sound yet. EGTs seem the same so far, but I haven't done any towing yet. Since I have a 4" downpipe and the cat is so far back I doubt I will see much diff in EGTs. There is no percievable difference in power, which I expected as all of my dyno testing with exhaust systems of various kinds I rarely see that much difference with or without cats....especailly one as big as the one on our trucks.
The only real difference I have noticed is there seems to be 0 smoke coming out of the exhaust when idling, without the cat I seemed to notice a slight amount of haze coming out of the exhaust at idle from time to time.
Thanks to everyone for your comments! Just wanted to pass along a simple idea in case others want or need to keep their cats and not lose any or much airflow with an aftermarket exhaust system.
Have a great weekend,
The only real difference I have noticed is there seems to be 0 smoke coming out of the exhaust when idling, without the cat I seemed to notice a slight amount of haze coming out of the exhaust at idle from time to time.
Thanks to everyone for your comments! Just wanted to pass along a simple idea in case others want or need to keep their cats and not lose any or much airflow with an aftermarket exhaust system.
Have a great weekend,
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From: Boca Raton, Florida
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From: Fallon,NV
Nice job on the fabrication! I'm hoping to have the same thing done to mine since the Magnaflow doesn't really come with a cat-retention pipe.
With the cat installed, does it sound the same as stock? I have no cat right now and it's absurdly loud with a weird "hiss" coming out the tailpipe. I'm just hoping that by welding the cat back in will quiet it back down to near-stock sound.
With the cat installed, does it sound the same as stock? I have no cat right now and it's absurdly loud with a weird "hiss" coming out the tailpipe. I'm just hoping that by welding the cat back in will quiet it back down to near-stock sound.
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From: W. Philly Burbs
Do you have a muffler installed? If not that will be needed if you want the truck be be close to near stock sound as you said.
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From: Fallon,NV
I took my truck to an exhaust professional and he's going to weld in a Dodge Cummins Cat back into the system since it already has a 4" inlet and outlet. That combined with getting the downpipe off the firewall should help quiet it down somewhat. If not, I'm not opposed to slapping the stock exhaust back in....I've gotta keep the lady happy!
Oh yeah, I did have the Magnaflow muffler on, but no cat.
Oh yeah, I did have the Magnaflow muffler on, but no cat.
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From: Fallon,NV
Dave,
I liked your set-up so much that I almost copied it on my Magnaflow system. But instead of the small Ford Cat, I went with a Dodge Cummins cat since it already has a 4" inlet/outlet and it's a lot larger in size. I love the sound of my system now....it really does just sound like a stock system except that it gets on it faster!
I liked your set-up so much that I almost copied it on my Magnaflow system. But instead of the small Ford Cat, I went with a Dodge Cummins cat since it already has a 4" inlet/outlet and it's a lot larger in size. I love the sound of my system now....it really does just sound like a stock system except that it gets on it faster!
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From: Western NC Mountains
Dc,
Glad that worked out for you!! Good idea on finding a larger factory cat. In my area it is Ford country, not too many of those Dodge thingys running around to snag a cat off of :-)
Glad that worked out for you!! Good idea on finding a larger factory cat. In my area it is Ford country, not too many of those Dodge thingys running around to snag a cat off of :-)
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From: Fallon,NV
Dave,
The Dodge Cat came from the exhaust man himself since he cut it out of his brand new Cummins and it was just sitting on a back shelf in his shop. It's amazing the size difference in the cat on the Cummins, of course, the Cummins also comes with a 4" factory exhaust.
As a side note, there won't be so many Cummins or Duramaxes driving around here anymore as the Chevy Dealership and the Dodge dealership both went under in the last 2 weeks. It's sad to see the economy, but at least Ford has the edge here now!
The Dodge Cat came from the exhaust man himself since he cut it out of his brand new Cummins and it was just sitting on a back shelf in his shop. It's amazing the size difference in the cat on the Cummins, of course, the Cummins also comes with a 4" factory exhaust.
As a side note, there won't be so many Cummins or Duramaxes driving around here anymore as the Chevy Dealership and the Dodge dealership both went under in the last 2 weeks. It's sad to see the economy, but at least Ford has the edge here now!
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