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Discussion Starter #1 (Edited)
So im looking on summit racing right now at long tube kooks, and looks like i can get the kooks long tubes with cats for around $1600. I think these are just the regular high flow cats not the "Green" cats. The green cats appear to be $1200.00 for just the cats alone.... What is the difference between the 2 and why is the green so much better?
 

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I used the knock off kooks header from eBay for 160$ and will never look back. I’ve run arh and kooks , the quality of these knock offs is on par and the price is unattainable elsewhere. There’s a good thread at lx about them. Kooks mids bolt right up , as do flow tech (no cats). I fabbed my own with flowmaster hf cats. But to go the flowtech route :
Headers :160-200$ depending which you find. I think they raised the price to 200 across the board though.
Flowtech non catted mids :240$
Gaskets and hardware: i used new oem. ~100$
O2 extensions: 79$


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The Green cats are rated for a higher horsepower and slightly better oxidizing according to Kooks without packing in etc. For most applications the regular high flow cats have been fine.
 

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Probably comes down the difference in the converters.

To properly process exhaust gases the exhaust gases must come into intimate contact with the working surfaces of the converter, working in that this is where the special metals reside that grab oxygen in the exhaust and then use this to, well, convert the bad exhaust gases into less bad exhaust gases.

A converter needs lots of surface area. This is generally provided for by the use of a monolithic honeycomb like structure. (Not exactly honeycomb in the cells are square not hexagonal.) This surface area is treated, washed, with a layer of carrier material into which is mixed/blended the catalyst metals. For the metals, platinum is preferred but at a cost of around $900/ounce other suitable metals are used, rhodium and palladium are the most common alternatives. In some cases iron, nickel, manganese, cerium, iron, even copper are used.

During manufacturing the carrier material "washes" over the surfaces of the honeycomb cells and binds to the surface of the honeycomb cells and in doing so generates a rough surface finish which helps increase the surface area and helps ensure the catalytic metals are exposed to intimate contact with the exhaust gases.

It needs to be mentioned this converter works at very elevated temperatures in the 600C range so the wash material needs to be able to withstand this heat and not melt and seal the metals against contact with the exhaust gases. Also the honeycomb material needs to be able to withstand this heat and also the shocks/loads it is subjected to as part of the exhaust system of the car. Auto makers are required to warranty the converters they fit to the vehicle for I believe 8 years or 80K miles, whichever comes first so this adds to the cost of the factory supplied exhaust system. Aftermarket exhaust system makers I believe are not obligated to offer any warranty other than what is required to be competitive with what other aftermarket exhaust system makers offer.

As an aside, I have to admit I think catalytic converters, O2 sensors, are very cool technology. Catalytic converter was invented by a French engineer back in the early 1930's and other people since have refined this technology to bring it where it is today.)

The cost of the raw materials, mainly the catalyst metals, is a factor, though that honeycomb structure doesn't grow on trees either, and the process to ensure a suitable coating/layer of wash material with a even blend of catalyst metals ends up on the surfaces of the honeycomb structure then the inserting this structure in an exhaust pipe all contribute to the cost of the "green" system over the other system.

'course, this assumes the "green" exhaust system is really better than the other one. To often a "green" label is applied to something to justify its higher price, but the actual level of greenness is questionable. I have no experience with either system so I have to take at face value the exhaust system manufacturer's claims that the green system is better. I will note neither system is approved for sale in CA.
 

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Kooks green cats have a higher cell count than their regular cats.
 

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I just removed my green cats off my car. No issues with them directly; however with my car being low I have scrapped them a couple of times and that makes me nervous with Alabama roads.

The scrapes have been exiting parking lots, so only cosmetic damage... but I was worried about catching a dip going 70 mph and ripping them off.. plus the header,etc.

If someone wants them.. let me know. We can discuss price... it will be a pretty good bargain.
 

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I believe the Green cats are 300 cell, are rated for up to 800 HP, and exhaust temperatures up to 1500°. They also are 49 state emissions legal. A Guy
 

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I just removed my green cats off my car. No issues with them directly; however with my car being low I have scrapped them a couple of times and that makes me nervous with Alabama roads.

The scrapes have been exiting parking lots, so only cosmetic damage... but I was worried about catching a dip going 70 mph and ripping them off.. plus the header,etc.

If someone wants them.. let me know. We can discuss price... it will be a pretty good bargain.
Are they still available?
 
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