[mlee]

Originally Posted by GT-ER

Because no muffler shop wants to touch my car without them. I've called and gone to a dozen of them and they all immediately steer me away if I don't have or want to install cats.

I'm in fort worth by the way.

Plenty of speed shops in your area that would take care of you. Check in with ADM Performance in Lewisville or with the Camaro club there for other recommendations.

Originally Posted by GT-ER

What cats were those?

ARH and I had run multiple 20 minute sessions on the road track in the heat of TX summer at 680 rwhp.

[GT-ER]

Originally Posted by SJFGTO

Power loss with green cats is minimal, 6-8 HP unless you are getting into upper level builds north of 800/850 or so. I still prefer the reliability of no cats with long tubes and a pulley. I have never found adding cats help much with drone, maybe a little. Cats do eliminate rasp which can occur with catless mids. Rasp and drone are 2 different things.

I don't think I'll ever go past 800whp to be honest. I hate raspy exhausts so yes, I hope it takes care of that.

[GT-ER]

Originally Posted by mlee

Plenty of speed shops in your area that would take care of you. Check in with ADM Performance in Lewisville or with the Camaro club there for other recommendations.

ARH and I had run multiple 20 minute sessions on the road track in the heat of TX summer at 680 rwhp.

I think I'll give the kooks green a shot. I barely do long pulls, just 60-140ish pulls every once in a while. Thanks for the suggestion though. I have kinda swayed towards acceptance...lol.

[staples87]

Originally Posted by Rlhay2

Run them at OEM AFR levels (very rich) and the unburnt fuel should help keep them from overheating.

It's actually the opposite. The richer the fuel, the more the cat has to work. In turn that's going to generate more heat, clog them and take them out.

[staples87]

Originally Posted by Dysan911

Interesting that this very topic came up. I have been seriously considering pulling the trigger and ordering some GESI Green HF cats for a couple reasons

1. The smell getting in/out of the car after pulling into the garage or if you're sitting at a red light with the windows down and the wind is just right. Ugh!. I feel self conscience about others when I am in a parking lot and people w/small kids are walking by as Im trying to back out of a spot or anyone in my wake.

2. I have a full ARH catback including LT Headers and had to get some resonators welded in to help cut the drone. They helped a lot and I'd say it went from a 10 being pretty bad to a 5 so I'm thinking with the green cats they might reduce the drone even further or possibly eliminate it entirely.

Overall I think I would enjoy driving my car a lot more with the HF Cats and I already spoke to my tuner about them and he agreed he too doesn't like a smelly car and that the green cats would not really effect performance.

Should also be easier to sell the entire setup as well should I ever decide to return to stock since I think most people prefer a legal exhaust setup with the cats.

What type/size resonators did you end up going with?

[gonabite]

Originally Posted by Rlhay2

Run them at OEM AFR levels (very rich) and the unburnt fuel should help keep them from overheating.

Yes, however its not the unburnt fuel, its the fact the cylinder temperatures are cooler with more fuel meaning cooler exhaust.

Originally Posted by staples87

It's actually the opposite. The richer the fuel, the more the cat has to work. In turn that's going to generate more heat, clog them and take them out.

Not correct at all. Exhaust temps are higher when running lean, and cooler when running rich. Creating a better environment for cats.

With half mile and mile racing you will run a more rich AFR to keep cylinder temps down and hopefully prevent detonation to to high cylinder temps, in turn mean cooler exhaust temps as well. Again a better environment for the cats.

[Can'tHave2MuchHP]

Originally Posted by staples87

It's actually the opposite. The richer the fuel, the more the cat has to work. In turn that's going to generate more heat, clog them and take them out.

Richer = Cooler exhaust temps = longer cat life. Period.

That's why COT (cat over-temp) protection mode makes the AFR rich(er), which creates lower temps in the cylinder/exhaust to protect the cats.

[Blueclyde]

Catalysts generally fail for one of two reasons. 1.) Excessive internal temperature due to uncontrolled combustion in the catalyst (generally from misfire). Multiple complete cyclinders of unburied air/fuel will drive temperatures up to extreme levels that will cause cordierite catalyst substrates to soften/melt. Metallic substrates may be more tolerant to this temperature but the catalyst wash coat will be damaged. There could be other events from aftermarket tuners, besides misfire, that cause events similar to misfire. 2.) Mechanincal failures due to vibrational accelerations experienced in the exhaust system while driving. Catalysts are ultimately connected to the engine and at high engine speeds, the exhaust can experience some significant vibrational input from the engine. The OEM spends a lot of time and money engineering and validating the factory exhaust system’s mechanical design and ultimately its durability. No way that aftermarket companies are undertaking this effort. I’ve got a little experience in this area. If I were going the aftermarket header and exhaust route, it is probably safest to not use their catalysts. It’s not technically legal either way, using the aftermarket catalysts or not, so it is safer to not (from a durability perspective) IMO.

[Dysan911]

Just curious if any of this applies to the GESI Green cats since they're rated to handle way more than i'd imagine the stock cats.

[Dysan911]

Originally Posted by staples87

What type/size resonators did you end up going with?

I am not exactly sure. I went to a local Muffler shop and they installed whatever they had on hand. They appear to be non-branded bottle style resonators. The are 3in Inlet/Outlet and about 18in long and they and do help tremendously.

[Can'tHave2MuchHP]

Originally Posted by Dysan911

Just curious if any of this applies to the GESI Green cats since they're rated to handle way more than i'd imagine the stock cats.

I believe it does apply to the GESI, though they're way better than your average high flow cat, they're still not R&D'd like a factory cat. See the highlighted below, which I highly agree with.

Originally Posted by Blueclyde

Catalysts generally fail for one of two reasons. 1.) Excessive internal temperature due to uncontrolled combustion in the catalyst (generally from misfire). Multiple complete cyclinders of unburied air/fuel will drive temperatures up to extreme levels that will cause cordierite catalyst substrates to soften/melt. Metallic substrates may be more tolerant to this temperature but the catalyst wash coat will be damaged. There could be other events from aftermarket tuners, besides misfire, that cause events similar to misfire. 2.) Mechanincal failures due to vibrational accelerations experienced in the exhaust system while driving. Catalysts are ultimately connected to the engine and at high engine speeds, the exhaust can experience some significant vibrational input from the engine. The OEM spends a lot of time and money engineering and validating the factory exhaust system’s mechanical design and ultimately its durability. No way that aftermarket companies are undertaking this effort. I’ve got a little experience in this area. If I were going the aftermarket header and exhaust route, it is probably safest to not use their catalysts. It’s not technically legal either way, using the aftermarket catalysts or not, so it is safer to not (from a durability perspective) IMO.

Agreed. Run cat-less and add a resonator/secondary muffler/bullets etc. if you don't like the sound, but don't run cats. If you really want to, a GESI/Kooks Green might hold up for you. But then again it might not. And if it doesn't, it can cause some pretty catastrophic damage and likely a few g-notes.

[Dysan911]

Originally Posted by Can'tHave2MuchHP

I believe it does apply to the GESI, though they're way better than your average high flow cat, they're still not R&D'd like a factory cat. See the highlighted below, which I highly agree with.


Agreed. Run cat-less and add a resonator/secondary muffler/bullets etc. if you don't like the sound, but don't run cats. If you really want to, a GESI/Kooks Green might hold up for you. But then again it might not. And if it doesn't, it can cause some pretty catastrophic damage and likely a few g-notes.

I'm not trying to change your opinion on this but have to say it seems contradictory to speak of the R&D that goes into the Factory Cats but then for the most part suggest folks go Catless and run resonators. Maybe I took something out of context or misunderstood your point and if so I apologize.

This is just me personally, I have a hard time swallowing that the factory cat is so much more highly R&D'd over a company that specializes solely in producing performance products that exceed manufacturer specifications. Keep in mind GESI isn't just a name, it stands for "Global Emissions Systems, Inc". All they do is design, development, and manufacture emissions control products for the past 20+ years..

It wouldn't surprise me to learn that GM outsources the stock Cats to the lowest bidding supplier they can find with some sort of financial protection warranty for them in place if suddenly they all start failing. I highly doubt the stock cats are any competition with a GESI cats.



Check these out: Vibrant Performance

Part Specifications
----------------------------------------------------------
Inlet / Outlet: 3.00"
Converter Body O.D. - 4.50"
Overall Length: 7.00"
Engine Limit Per Bank: 500-850HP
Substrate Cell Count: 300 cells / inch^2


GESI High Output (HO-series) and Ultra High output (UHO-series) Universal Metal Core Catalytic Converters have been designed to provide a reliable solution to the most common converter problems experienced by our customers.

- EPA certified for use on OBD2 vehicles (1996 and newer). 49 States only!
- Full Stainless Steel construction, including the substrate which is furnace braised to the mantle for outstanding durability
- Unique end-cap design locks substrate in so it can't rattle around
- The GESI proprietary precious metal loading technology ensures greatly reduced emissions, eliminating most "Check Engine Light" issues
- Capable of withstanding up to 1500 deg F
- Ideal for forced induction applications, with no loss of HP
- Covered by a 5 y


https://youtu.be/56oLVgpwOAs


I don't track my car and with as heavy as traffic is around me I'd be lucky if I can find a long empty on-Ramp that I can open it up on once in a while so I'd say 95% time I am not beating on it. I just want to reduce or eliminate the awful gas smell and if possible reduce the drone some. I am confident a company like Vibrant makes a quality product and even backs it up with a 5yr warranty that it'll just work out fine.

[GT-ER]

So I ended up NOT installing the kooks green and am currently having magnaflow 200 cell metallic cats installed. They actual look like they flow better than the kooks green (lower cell count and it even has a hole in the middle that goes straight through. It was so much cheaper and honestly, if they end up breaking, I'll just gut them and leave it like that. I don't even have rear O2's to worry about. I love the catted sound and lack of smell so I'll just give these a shot.

[Can'tHave2MuchHP]

Originally Posted by Dysan911

I'm not trying to change your opinion on this but have to say it seems contradictory to speak of the R&D that goes into the Factory Cats but then for the most part suggest folks go Catless and run resonators. Maybe I took something out of context or misunderstood your point and if so I apologize.

This is just me personally, I have a hard time swallowing that the factory cat is so much more highly R&D'd over a company that specializes solely in producing performance products that exceed manufacturer specifications. Keep in mind GESI isn't just a name, it stands for "Global Emissions Systems, Inc". All they do is design, development, and manufacture emissions control products for the past 20+ years..

It wouldn't surprise me to learn that GM outsources the stock Cats to the lowest bidding supplier they can find with some sort of financial protection warranty for them in place if suddenly they all start failing. I highly doubt the stock cats are any competition with a GESI cats.



Check these out: Vibrant Performance

Part Specifications
----------------------------------------------------------
Inlet / Outlet: 3.00"
Converter Body O.D. - 4.50"
Overall Length: 7.00"
Engine Limit Per Bank: 500-850HP
Substrate Cell Count: 300 cells / inch^2


GESI High Output (HO-series) and Ultra High output (UHO-series) Universal Metal Core Catalytic Converters have been designed to provide a reliable solution to the most common converter problems experienced by our customers.

- EPA certified for use on OBD2 vehicles (1996 and newer). 49 States only!
- Full Stainless Steel construction, including the substrate which is furnace braised to the mantle for outstanding durability
- Unique end-cap design locks substrate in so it can't rattle around
- The GESI proprietary precious metal loading technology ensures greatly reduced emissions, eliminating most "Check Engine Light" issues
- Capable of withstanding up to 1500 deg F
- Ideal for forced induction applications, with no loss of HP
- Covered by a 5 y


https://youtu.be/56oLVgpwOAs


I don't track my car and with as heavy as traffic is around me I'd be lucky if I can find a long empty on-Ramp that I can open it up on once in a while so I'd say 95% time I am not beating on it. I just want to reduce or eliminate the awful gas smell and if possible reduce the drone some. I am confident a company like Vibrant makes a quality product and even backs it up with a 5yr warranty that it'll just work out fine.

I only read the first piece but resonators/mufflers are completely different than cats (Any kind). Cats are usually packed with dense material. Resonators or mufflers are usually tubes/boxes with different chambers sectioned off by vertical pieces of steel with plenty of clear flow and no wall of particulate/material. Not even close.

I'm aware what GESI is...

Please note, my entire post is my opinion based on experience and discussion on multiple forums...I don't like rasp/smell/obnoxious exhaust anymore than the next guy. And yet, I still would recommend catless, so that should tell you something.