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Catted OR Catless downpipe

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davie
#1
Looking into getting a downpipe here pretty soon. My current set up is just straight pipe (with only thing left is stock DP W/cat). I am wondering if anybody runs a cat-less DP here and what their thoughts on it are? I live in FL so emissions is not an issue. Everyone give me your opinion's!
 


M-Sport fan

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#3
If you can handle the STENCH, and the ricer RASP of a catcon-less down pipe and straight pipe system, go for it. ;)
 


TDavis

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#4
If you can get by without a cat I feel its a toss up. I'm sure some want to hear the turbo whistle so they want a catless but its always an issue that a catless DP can mess up your exhaust note if you already have a nice exhaust note on the car.
 


Clint Beastwood

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#6
If you can get by without a cat I feel its a toss up. I'm sure some want to hear the turbo whistle so they want a catless but its always an issue that a catless DP can mess up your exhaust note if you already have a nice exhaust note on the car.
He’s straightpiped so catless can’t make it sound much worse. Might as well, it’s already blatty.
 


jeff

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#7
Emissions is always an issue.
This.

To the OP, I'm glad you asked about this and are thinking about it. Of course, there are definite health issues and possible legal and ethical/environmental issues surrounding putting a catless DP on a car for street use. Those aside, there is another issue, which is the unpleasant smell. Assuming you don't run the A/C all the time (because you like fresh air or don't want the power drain), and your windows are open............do you want that smell every time you slow down or stop or park the car? Along with destroying your lungs and those of the people around you, the smell gets no fun after a few days. Get to your destination and your hair and clothes smell like exhaust. Is it worth it for 5-10 more HP? I say no. I mostly drive around with my windows open and I can always tell when someone is catless. If it's a classic car it's one thing, that's how they all smell. But a newish car that eliminates the cat on purpose is another.

Yeah I'm opinionated but you asked. I'm not a tree hugger, but aside from environment there are many other reasons why I think catless is not the best choice.

Just my .02, not saying I'm right, just how I think.

*****
PS by the way unless you go bigger/hybrid turbo, DP is not going to help you. DP will bring gains down low but it robs power up high. Why add more power where the car doesn't need it (wheels spinning at 2500rpms) - a waste - while robbing power where the car does need it (5000rpms and higher)? This has been proven beyond dispute years ago. So unless you just want more power to shred your tires in 1st and 2nd gear, which provides the illusion of speed but in reality means you're not moving forward, don't get a catless DP.
 


TDavis

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#8
PS by the way unless you go bigger/hybrid turbo, DP is not going to help you. DP will bring gains down low but it robs power up high. Why add more power where the car doesn't need it (wheels spinning at 2500rpms) - a waste - while robbing power where the car does need it (5000rpms and higher)? This has been proven beyond dispute years ago. So unless you just want more power to shred your tires in 1st and 2nd gear, which provides the illusion of speed but in reality means you're not moving forward, don't get a catless DP.
Not saying you're wrong but what about Cobbs dyno sheet of their stage 3 fiesta? You still see gains throughout the curve when going from stage 2 to stage 3 which the only difference between the two is an added DP.
 


jeff

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#9
Not saying you're wrong but what about Cobbs dyno sheet of their stage 3 fiesta? You still see gains throughout the curve when going from stage 2 to stage 3 which the only difference between the two is an added DP.
That's a good point. I may sound like a conspiracy theorist here but these views go back years ago and are based on some good old honest objective data so bear with me.

And BTW I love Cobb and Mountune for the support they've given our cars. I have their stuff on my car. But they are out to make money, period.

Cobb or whomever is out to sell a product. Therefore, they create tiered "stages" so that you and I think that if we buy X package we get Y power. A tune can be calibrated any way the tuner wants. It's interesting to me that in all those power gains that Cobb provided they still created tunes that scorched the tires in 1st and 2nd gear. They added all that power but it wasn't usable. Most every review I've seen of the Cobb staged packages has the reviewer in a state of ecstasy over how "1st and 2nd gear are useless". To me, that shows a lack of balance. Most of the power gains on a stock turbo - 90% I daresay - are in the tune. Even without an upgraded intercooler one can tune in the same numbers as a car with an upgraded one - the difference will be how long it can maintain power because of whichever intercooler. Either car can make the same power when relatively cold on a dyno - only the one with an upgraded FMIC will make it longer and more consistently. Back to the tune - a tuner can make the car do whatever he wants. He can limit the PSI or he can blow up the turbo on purpose, it's all in the tune. The Cobb tunes are what created those beautiful lines you refer to. They they give people like Matt Farah their products, free and installed free, he gets a zillion views and they make tons of money for his review. It's capitalism at it's finest, and many of us fell for it. On that note, who cares - I wanted a bigger FMIC and exhaust because it's fun and sounds great and I love installing. Plus I was considering turbo upgrade so I wanted the right hardware in place for that.

Anyhow, I suggest that the curves you refer to are created intentionally to sell a product. Put them next to a custom tuned car with zero hardware upgrades and you'll be surprised that the custom tune has the same numbers safely without hardware. All of this info BTW is buried in various threads on this forum, I can't dig it up right now but it's there. Most of the old school folks from 2014-2015 are gone now but they are the ones that discovered all of this a few years ago.

Personal proof, Mountune claims their CBE adds power to my car. I didn't think it would, but wanted sound. I installed it, had my tuner look at logs, and no surprise no tune upgrade was needed. There was no power to be gained, period, on the stock turbo setup with this hardware upgrade. My tuner has done about 50 tune revisions for me. It wasn't a case of him not wanting to work more. There was no more power to be found so he didn't adjust the tune. He has the other 49 times so the issue is not him, it's the hardware which simply doesn't make the car faster.

Anyhow hope that helps. The DP robbing top end power is a different discussion, but all of that was also documented back in the day. Dig for it or just trust me.
 


kevinatfms

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#10
Today's stock 3 way converters are quite efficient on cars in factory form. Even lightly modified they dont restrict as much as people think or at all. I dont think ill ever run another vehicle without a cat again.

Im waiting for Whoosh Motorsports 200 cell catalytic converter to come out before i swap my C39 on.
 


TDavis

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#11
That's a good point. I may sound like a conspiracy theorist here but these views go back years ago and are based on some good old honest objective data so bear with me.

And BTW I love Cobb and Mountune for the support they've given our cars. I have their stuff on my car. But they are out to make money, period.

Cobb or whomever is out to sell a product. Therefore, they create tiered "stages" so that you and I think that if we buy X package we get Y power. A tune can be calibrated any way the tuner wants. It's interesting to me that in all those power gains that Cobb provided they still created tunes that scorched the tires in 1st and 2nd gear. They added all that power but it wasn't usable. Most every review I've seen of the Cobb staged packages has the reviewer in a state of ecstasy over how "1st and 2nd gear are useless". To me, that shows a lack of balance. Most of the power gains on a stock turbo - 90% I daresay - are in the tune. Even without an upgraded intercooler one can tune in the same numbers as a car with an upgraded one - the difference will be how long it can maintain power because of whichever intercooler. Either car can make the same power when relatively cold on a dyno - only the one with an upgraded FMIC will make it longer and more consistently. Back to the tune - a tuner can make the car do whatever he wants. He can limit the PSI or he can blow up the turbo on purpose, it's all in the tune. The Cobb tunes are what created those beautiful lines you refer to. They they give people like Matt Farah their products, free and installed free, he gets a zillion views and they make tons of money for his review. It's capitalism at it's finest, and many of us fell for it. On that note, who cares - I wanted a bigger FMIC and exhaust because it's fun and sounds great and I love installing. Plus I was considering turbo upgrade so I wanted the right hardware in place for that.

Anyhow, I suggest that the curves you refer to are created intentionally to sell a product. Put them next to a custom tuned car with zero hardware upgrades and you'll be surprised that the custom tune has the same numbers safely without hardware. All of this info BTW is buried in various threads on this forum, I can't dig it up right now but it's there. Most of the old school folks from 2014-2015 are gone now but they are the ones that discovered all of this a few years ago.

Personal proof, Mountune claims their CBE adds power to my car. I didn't think it would, but wanted sound. I installed it, had my tuner look at logs, and no surprise no tune upgrade was needed. There was no power to be gained, period, on the stock turbo setup with this hardware upgrade. My tuner has done about 50 tune revisions for me. It wasn't a case of him not wanting to work more. There was no more power to be found so he didn't adjust the tune. He has the other 49 times so the issue is not him, it's the hardware which simply doesn't make the car faster.

Anyhow hope that helps. The DP robbing top end power is a different discussion, but all of that was also documented back in the day. Dig for it or just trust me.
Yeah I plan on upgrading my turbo once the warranty is up so thats what I'm going for.

I think its all personal preference. There are plenty of threads out there with people who have had their car dyno'd and have shown gains, even the same exact gains as Cobb advertises...on the other hand I'm sure there are probably equal amount of threads saying what you're saying. But I feel if the latter was 100% true then people wouldn't go with Cobb or Mountune as much as they do so the formal is preferred. Yeah I agree they can make those gains to sell their product but that doesn't mean their product is lying. You can still get the same gains they get, you just need a specified tune sometimes. They've built their OTS tunes for the majority of peoples vehicles, since a lot of things vary from car to car, so that people don't always need to go to Cobb Pro Tuners to get the most out of their products, or any tuner for that matter. I still think the formal outweighs the latter in this situation.

I'm sure a person at Cobb could explain it better then both of us on what timing tables, ignition corrections, etc. are put into the different tunes to compensate for a aftermarket DP, intercooler, intake, or exhaust being newly added to the car. They do have blogs/notes and info that explain how they tune ECU's on their website and how power is gained through their corrections. They also explain it to you so that you can try to tune it yourself if you so desire.
 


jeff

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#12
Yeah I plan on upgrading my turbo once the warranty is up so thats what I'm going for.

I think its all personal preference. There are plenty of threads out there with people who have had their car dyno'd and have shown gains, even the same exact gains as Cobb advertises...on the other hand I'm sure there are probably equal amount of threads saying what you're saying. But I feel if the latter was 100% true then people wouldn't go with Cobb or Mountune as much as they do so the formal is preferred. Yeah I agree they can make those gains to sell their product but that doesn't mean their product is lying. You can still get the same gains they get, you just need a specified tune sometimes. They've built their OTS tunes for the majority of peoples vehicles, since a lot of things vary from car to car, so that people don't always need to go to Cobb Pro Tuners to get the most out of their products, or any tuner for that matter. I still think the formal outweighs the latter in this situation.

I'm sure a person at Cobb could explain it better then both of us on what timing tables, ignition corrections, etc. are put into the different tunes to compensate for a aftermarket DP, intercooler, intake, or exhaust being newly added to the car. They do have blogs/notes and info that explain how they tune ECU's on their website and how power is gained through their corrections. They also explain it to you so that you can try to tune it yourself if you so desire.
I never said that Cobb was lying, I don't think that's the case. I'm just saying that they make the tunes look the way they want them. Those beautiful tiered dyno plots look that way on purpose, they could have made them look however using the tune parameters without respect to the hardware added.

And you're right about the OTS being a generic tune for many vehicles versus one specific custom situation. That said I actually really like the Cobb OTS tunes, they are decent enough for what you pay for, and safe, though not very balanced, but they gave the people what they wanted, MOAR POWR which satisfies most power-hungry people even if all that's happening is the tires spinning.

Sounds like a good plan, good luck with the turbo upgrade.
 


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#13
Having gone from a cobb catted DP to a DHM catless, theren s a difference. 1 being a noticeable power gain. I am on a hybrid turbo. The x47r to be exact. Yes it smells occasionally and can get annoying but its not terrible. The perks of catless are the occasional pops and crackles. Those are fun. Weigh the options. Catted is definately cleaner and no smell or emmisions. Catless is also cheaper. You decide.
 


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#14
I 100% agree that hitting up Whoosh is a solid plan for a downpipe. I am anxiously watching to see the reviews on the catted version before I decide if I want to upgrade to a full 3" exhaust or not. At this point, I don't because I don't want the noise, but then again I like to tinker and try products so who knows.

If its your daily, my vote would be a catted version. But I guess that's just the direction my tastes have headed over the years. One if its the car I'm going to do a lot of miles in, making the exhaust I put out a little cleaner sounds good in my head. I look for a certain sound from my daily driver and one of which involves a quieter, less raspy tone, but again that's because I'm in it everyday. I utterly hate mornings so commuting with a loud exhaust or obnoxious induction noise would just make me irritated. Now if not a daily, I'm all for squeezing every ounce of power out. My MR2 is t3/t4 turbo, 3" exhaust no cats, 4" intake and it used to have a open dump tube off the wastegate.

But you're in Florida, they don't even have inspections... so either way works in that aspect. Just pick what suits your taste. Its not a super fun job to do, so hope you pick the right option the first time.
 


ron@whoosh

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I 100% agree that hitting up Whoosh is a solid plan for a downpipe. I am anxiously watching to see the reviews on the catted version before I decide if I want to upgrade to a full 3" exhaust or not. At this point, I don't because I don't want the noise, but then again I like to tinker and try products so who knows.

If its your daily, my vote would be a catted version. But I guess that's just the direction my tastes have headed over the years. One if its the car I'm going to do a lot of miles in, making the exhaust I put out a little cleaner sounds good in my head. I look for a certain sound from my daily driver and one of which involves a quieter, less raspy tone, but again that's because I'm in it everyday. I utterly hate mornings so commuting with a loud exhaust or obnoxious induction noise would just make me irritated. Now if not a daily, I'm all for squeezing every ounce of power out. My MR2 is t3/t4 turbo, 3" exhaust no cats, 4" intake and it used to have a open dump tube off the wastegate.

But you're in Florida, they don't even have inspections... so either way works in that aspect. Just pick what suits your taste. Its not a super fun job to do, so hope you pick the right option the first time.
this week!
pallet load of catted and catless!

 


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San Jose
#20
Looking into getting a downpipe here pretty soon. My current set up is just straight pipe (with only thing left is stock DP W/cat). I am wondering if anybody runs a cat-less DP here and what their thoughts on it are? I live in FL so emissions is not an issue. Everyone give me your opinion's!
No point in running around catless on a stock turbo, unless you’re trying to (poorly) imitate a modified diesel truck.


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