CAT Delete Question
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Junior User
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CAT Delete Question
I know there are a couple of exhaust threads going, but I didn't want to hijack them.
I am wanting to put 4" exhaust on my stock truck but have some questions.
I am wanting to put 4" exhaust on my stock truck but have some questions.
- Will going to 4" exhaust while keeping the stock CAT in place still help with the EGT's?
- Is it pointless to add 4" exhaust and keep the CAT?
- Is it better to go with 3.5" down pipe and then 4" or just go 4" all the way? (Without being tuned, am I going to run into any back pressure problems?)
- Should I just remove the CAT and keep it around for warranty work and emissions time?
Posting Guru
Joined: Sep 2009
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From: Virginia beach, VA
1. With a 4 inch exhaust and CAT still in place you will see little if any EGT reduction.
2. Yes, IMO
3. Some trucks have a problem with clearance with a 4" down pipe. I would personally keep the stock 3" down pipe but thats up to you, some people do 4" the whole way.
4. Yes. You never know what kind of emissions laws your state may implement in the future, and if you toss your CAT buying a new one is not cheap.
Hope that helped..
2. Yes, IMO
3. Some trucks have a problem with clearance with a 4" down pipe. I would personally keep the stock 3" down pipe but thats up to you, some people do 4" the whole way.
4. Yes. You never know what kind of emissions laws your state may implement in the future, and if you toss your CAT buying a new one is not cheap.
Hope that helped..
Logistics Pro
Joined: May 2004
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You will be better of ditching the CAT and muffler
I know there are a couple of exhaust threads going, but I didn't want to hijack them.
I am wanting to put 4" exhaust on my stock truck but have some questions.
I am wanting to put 4" exhaust on my stock truck but have some questions.
- Will going to 4" exhaust while keeping the stock CAT in place still help with the EGT's?Not much, the CAT retains ALOT of the heat
- Is it pointless to add 4" exhaust and keep the CAT? Well it depends what you mean by pointless.....remove the CAT and you remove a MAJOR restriction and lower EGT's (major) ....kepp it but you stay legal and run hotter than necessary....so you decide
- Is it better to go with 3.5" down pipe and then 4" or just go 4" all the way? (Without being tuned, am I going to run into any back pressure problems?)When I bought my BANKS in 2004 that is all there really was and the downpipe is 3.5" for clearance issues, the rest is true 4". No you will not have any BP problems. If I understand it correctly, the turbo creates all of the BP you need, the rest is just restriction.
- Should I just remove the CAT and keep it around for warranty work and emissions time?YEP and while youre at it, ditch the muffler and straight pipe it. I was hesitant but made the decision quickly after removing the CAT and keeping the muffler....my truck sounded ridiculous (IMO). I had a local muffler shop make me a slip in piece where the CAT goes and a 2' extension where the muffler was and dumped it right in front of the rear diff tube with a SS 90* turndown. It sounds awesome......looks good and my vehicle even running MATT's SRL RARELY reaches 1250* (it will but it takes a bit as opposed to running with CAT and muffler).
IMO the sound and performance from a straight exhaust on this truck is unmatched. I will admit it gets a little noisy sometimes but that is why you have windows
Logistics Pro
Joined: Mar 2007
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From: Claremore, OK
^^^ I'd agree. Besides, for $20-$30 you should be able to buy a straight pipe out of a wrecked '98-'02 SD at your local salvage yard...that will bolt right place of the kitty. And it would take less than a 1/3 of the effort. That's what I did to mine until I go with a 4" turbo back someday.
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That was my concern with gutting the cat. I hear of a lot of guys doing it, but never thought it was a good idea. With the way every thing is, you never know when you'll need it.
Thanks for all your input. I think I might stay with the stock downpipe, remove the cat and go 4" the rest of the way. When I get tuned later down the road I could always change the downpipe. Just a thought anyways.
Thanks for all your input. I think I might stay with the stock downpipe, remove the cat and go 4" the rest of the way. When I get tuned later down the road I could always change the downpipe. Just a thought anyways.
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Post Fiend
Joined: Oct 2005
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From: Plano TX and Brentwood TN
No, it isn't pointless. For 2 points at least.
- These aren't the HP robbing Cats that may parents had to deal with when were growing up.
- If you live in the US, it is against Federal law to remove and/or modify emissions equipment that came on your vehicle from the factory. Regardless if you have emissions testing or not. Emissions testing just improves your chances of getting caught.
There is very little to gain by removing the Cat unless you just want to either for sound or you for some reason believe it gets you more. These aren't the restrictive Cats that people think that they are and plus like I said before, even if you don't have emissions testing (yet), it's still against the law to remove it or modify it. You can only remove to either replace or repair. Also the replace has to certified as well.
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Tex,
I definitely can attest to the lowering of EGT's drastically when I removed the CAT....that is just my opinion. The numbers would shoot really high, really quick....now without it the numbers climb quick but nowhere near as before...
Even in stock form with the CAT I'd have to let off when towing my huge trailer just to keep the EGT's from exceeding 1250*....now it will reach 1250* but not as fast and it will not keep climbing.
I definitely can attest to the lowering of EGT's drastically when I removed the CAT....that is just my opinion. The numbers would shoot really high, really quick....now without it the numbers climb quick but nowhere near as before...
Even in stock form with the CAT I'd have to let off when towing my huge trailer just to keep the EGT's from exceeding 1250*....now it will reach 1250* but not as fast and it will not keep climbing.
Post Fiend
Joined: Oct 2005
Posts: 10,626
Likes: 7
From: Plano TX and Brentwood TN
Tex,
I definitely can attest to the lowering of EGT's drastically when I removed the CAT....that is just my opinion. The numbers would shoot really high, really quick....now without it the numbers climb quick but nowhere near as before...
Even in stock form with the CAT I'd have to let off when towing my huge trailer just to keep the EGT's from exceeding 1250*....now it will reach 1250* but not as fast and it will not keep climbing.
I definitely can attest to the lowering of EGT's drastically when I removed the CAT....that is just my opinion. The numbers would shoot really high, really quick....now without it the numbers climb quick but nowhere near as before...
Even in stock form with the CAT I'd have to let off when towing my huge trailer just to keep the EGT's from exceeding 1250*....now it will reach 1250* but not as fast and it will not keep climbing.
Also hills, or going against the wind etc, those will cause EGTs to get higher than without those variables.
Now granted we do have different configurations etc on the truck, so I'm sure that's going to be one of those things that's going to vary between vehicle to vehicle and driving habits etc. Than of course, you have the whole alum. versus SS debate as well.
One thing that would keep me for sure from eliminating it would be that it's against the law for sure if you live in any state within the US. If you do get caught, whatever savings etc that you think you are getting from removing the cat is null and void with that fine for a looooonnnngggg time. Now odds are either more or less depending if you have emissions testing, but you can still be fined even if there is no testing in that area for diesel.
Logistics Pro
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I hear you on the variables.....and I totally agree. Hey you know I always wanted to ask you since I have heard you mention several times in regards to ALL of the engine mods you did.....any chance you'd list em?
Thanks
Thanks
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Like usual, every time I think about modding my truck (tuner, exhaust...whatever) something convinces me to leave it stock. Back in my younger days I would have made the changes without a thought, these days it's murphys law,what can go wrong more than likely will. I still want to modify the exhaust for towing/EGT purposes, so more than likely (for now any ways) I will just go 4", CAT back. Later this summer, or even next year, I may buy an SCT from Matt (Gearhead) and go from there, maybe even wait until I get the thing studded.
Thanks for all you input so far. What non-illegal, simple and cheap mods have you all done? Something I can do in the meantime to boost the performance, MPG, or plain running of the truck. I enjoy doing the work, and this is the first tuck I have owned in a long time that I actually want to do anything on.
Thanks for all you input so far. What non-illegal, simple and cheap mods have you all done? Something I can do in the meantime to boost the performance, MPG, or plain running of the truck. I enjoy doing the work, and this is the first tuck I have owned in a long time that I actually want to do anything on.
Cross-Country
Joined: Jun 2010
Posts: 99
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From: Featherville, Idaho
Okay my fellow green handles. You convinced me. Guess I will invest money in a 4" exhaust system then some gauges. Any brand/model you recommend (both exhaust and gauges)? Then later down the line a tuner. My problem though is I probably won't have them installed by the 1st of June start date of towing my fifth wheel 5,000 mile trip. BUMMER!! 
Logistics Pro
Joined: May 2004
Posts: 3,616
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Like usual, every time I think about modding my truck (tuner, exhaust...whatever) something convinces me to leave it stock. Back in my younger days I would have made the changes without a thought, these days it's murphys law,what can go wrong more than likely will. I still want to modify the exhaust for towing/EGT purposes, so more than likely (for now any ways) I will just go 4", CAT back. Later this summer, or even next year, I may buy an SCT from Matt (Gearhead) and go from there, maybe even wait until I get the thing studded. -THIS IS THE KEY and will damn near make your truck bulletproff (within reason).
Thanks for all you input so far. What non-illegal, simple and cheap mods have you all done? Something I can do in the meantime to boost the performance, MPG, or plain running of the truck. I enjoy doing the work, and this is the first tuck I have owned in a long time that I actually want to do anything on.
Thanks for all you input so far. What non-illegal, simple and cheap mods have you all done? Something I can do in the meantime to boost the performance, MPG, or plain running of the truck. I enjoy doing the work, and this is the first tuck I have owned in a long time that I actually want to do anything on.
Cross-Country
Joined: Jun 2010
Posts: 99
Likes: 0
From: Featherville, Idaho
4" pipe
Joe Blow and Tex25025, just reading your posts has helped a lot. I am going to go to a 4" pipe. My question is can I get away with going 4" after the Cat only? I want to also install gauges I soon as I can decide what type, a lot of them to choose from, and of course everyone of them are "THE BEST ON THE MARKET." 
I have a 2005 F-250 6.0L and will be towing a 32' fifth wheel travel trailer, which, by the sticker on the trailer says the max weight loaded is around 13,888 lbs. All though I'll never load that much in it to get close to that number.
The only things I have done so far is install a coolant filter system and will be installing Firestone Air Bags tomorrow.
Any help or advice from you and anyone else will be greatly appreciated!
I have a 2005 F-250 6.0L and will be towing a 32' fifth wheel travel trailer, which, by the sticker on the trailer says the max weight loaded is around 13,888 lbs. All though I'll never load that much in it to get close to that number.
The only things I have done so far is install a coolant filter system and will be installing Firestone Air Bags tomorrow.
Any help or advice from you and anyone else will be greatly appreciated!
Last edited by jayhawk714; May 26, 2011 at 05:02 PM. Reason: Adding name