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High Flow Cat Vs Decat

Dylaan

By Dylaan,
in Engines & Forced Induction

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karma_syke Collaborator

karma_syke

Posted
Posted

Not true. A cat that is working stores a lot of heat compared to a gutted cat so all the epa need is an infra-red thermometer to check it's temp compared to the rest of the exhaust.

doesn't the stock cat have a heat shield on it? then they'd have to get under your car and take it off to see the surface temp of the cat. which means it needs to be on a hoist. which means you're at an EPA station, which means you've been issued an EPA notice already...

point is. could any cop/road side inspection tell that your running a 'decat' inside a cat shell.

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cannabiscorpse Mentor

cannabiscorpse

Posted
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Very highly doubt a cop could tell you have a decat. Unless they have emissions testing equipment?

Either way if you are at an epa station, you arent going to keep the decat on the car. Regardless of the method they use, they will pick you up for a gutted cat, everytime. You would have to be a complete idiot to turn up for your epa inspection with a gutted cat.

Tony de Wonderful Veteran

Tony de Wonderful

Posted
Posted

doesn't the stock cat have a heat shield on it? then they'd have to get under your car and take it off to see the surface temp of the cat. which means it needs to be on a hoist. which means you're at an EPA station, which means you've been issued an EPA notice already...

point is. could any cop/road side inspection tell that your running a 'decat' inside a cat shell.

They might confiscate it off you first. Then you wouldn't be able to re-cat it.

Dylaan Veteran

Dylaan

Posted
  • Author
Posted

Is there that much of a flow difference that you could notice the difference between a 100cell cat and a decat? I've looked inside a 100cell cat before and it just looks like a punch of mcdonnald's straws stuck together? I'm sure it would make some filtration difference but I don't think the difference would be huge. If I did do the decat and somebody confiscated it off me I will have a spare one anyway.

I got defected last week when I wasn't doing anything wrong, If I was hooning I would understand but I don't feel like getting a road worthy again.

cannabiscorpse Mentor

cannabiscorpse

Posted
Posted

Is there that much of a flow difference that you could notice the difference between a 100cell cat and a decat? I've looked inside a 100cell cat before and it just looks like a punch of mcdonnald's straws stuck together? I'm sure it would make some filtration difference but I don't think the difference would be huge. If I did do the decat and somebody confiscated it off me I will have a spare one anyway.

I got defected last week when I wasn't doing anything wrong, If I was hooning I would understand but I don't feel like getting a road worthy again.

I dont think there is too much flow difference mate. Im assuming the car is a mild streeter, in which case i really dont think you would notice the difference between the two. As far as having your car confiscated, im pretty sure you have to be drag racing or doing burnouts etc that warrant a dangerous driving charge. In either case i can say that a decat will be the least of your worries. I think it comes down to your preference, and whether you want the peace of mind of not running a decat. For me, i just bought a hiflow because i didnt want the hassle of worrying about it. I even left it on the car when it went to the epa, and he just said it 'may' pass, but it would need engineer certificate.

karma_syke Collaborator

karma_syke

Posted
Posted

I dont think there is too much flow difference mate. Im assuming the car is a mild streeter, in which case i really dont think you would notice the difference between the two. As far as having your car confiscated, im pretty sure you have to be drag racing or doing burnouts etc that warrant a dangerous driving charge. In either case i can say that a decat will be the least of your worries. I think it comes down to your preference, and whether you want the peace of mind of not running a decat. For me, i just bought a hiflow because i didnt want the hassle of worrying about it. I even left it on the car when it went to the epa, and he just said it 'may' pass, but it would need engineer certificate.

i suppose his decision is going to be based off how much a decat flows better/gains power/ less lag over a highflow cat versus the risk of being ass raped by the state government.

i don't think anybody here actually has any quantitative answer to how much decat flows better only that 'it does'.

ARTZ Grand Master

ARTZ

Posted
Posted

Exactly ...way i see it there is nothing to be gained on the street from removing pollution gear so why not just keep it . Pretty sure I read somewhere that race/drift cars in Japan are required to keep pollution gear and they are hardly slow.

Whats it worth really ,10hp maybe at most, on a 400hp+ car its a pittance so just keep it and you will be doing the planet a favour . Just have a decat for the track if you want it and block of your charcoal cannister its not hard to change..

Do the right thing :D

PS.. This thread is stupid.....

cannabiscorpse Mentor

cannabiscorpse

Posted
Posted

all i know is you can get up to 20bhp gain from having a highflow cat!

in gran turismo 5 ofcourse..

Lmfao!! I bet Paul didnt run a cat in his supra in fast and the furious!

Seriously though, i agree with what arthur has said, but in the end it comes down to preference. Someone really needs to do a dyno run back to back with different cats to put this to rest, although i suspect the gains/losses in hp would be so little that it would just come down to different dyno runs.

Dylaan Veteran

Dylaan

Posted
  • Author
Posted

the way I see it is that with a decat I can get an EPA, with a highflow I can get an EPA. Cops won't know it's a decat if the shell is still on it.

I want my car to sound a little bit more beefy than it does at the moment, but I don't want to be shattering glass as I drive past houses.

I don't really think it is easy to tell if a 2.5inch decat or a 3inch highflow cat has better flow without the use of something like a dyno test.

I've got a few weeks to think about it since I'm heading overseas next week.

Hanaldo Grand Master

Hanaldo

Posted
Posted

the way I see it is that with a decat I can get an EPA, with a highflow I can get an EPA. Cops won't know it's a decat if the shell is still on it.

I want my car to sound a little bit more beefy than it does at the moment, but I don't want to be shattering glass as I drive past houses.

I don't really think it is easy to tell if a 2.5inch decat or a 3inch highflow cat has better flow without the use of something like a dyno test.

I've got a few weeks to think about it since I'm heading overseas next week.

With a good quality high flow cat you can pass an EPA. I think given there is barely any difference between a good high flow and a 3" decat, the high flow is the better option.

Dylaan Veteran

Dylaan

Posted
  • Author
Posted

With a good quality high flow cat you can pass an EPA. I think given there is barely any difference between a good high flow and a 3" decat, the high flow is the better option.

but do the benefits outweigh the extra cost?

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