[GT-ER]

I see cars like the Bugatti Chiron and Koenigsegg Regera pushing well over 1000hp with EPA compliant Cat Converters yet read here that cats will melt if you push them at those power levels. Am I missing something?

I may be forced to install cats on my car, which I don't really mind much since I know that low cell cats aren't super restrictive, and am hoping to, in the future, put down at least 800whp but am afraid of getting cats that will just autodestruct. I've been talking to a shop and the guy says that the magnaflow 200 cell converters he uses will be fine for my application.

Has no one had good luck with cats on high powered cars? I don't need my car to pass emissions testing by the way so I don't need super clean cats, just cats that flow well and won't self destruct.

[soceur77]

I'm going with a GESI Green cat distributed via Kooks.

[Rlhay2]

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

[GrabTheWheel]

Replacing the catalytic converters on the cars you mentioned probably costs more than a brand new ZL1. Not sure that makes them any better than what's on a regular car though...

[mlee]

At 800 you're will definitely want to ditch the cats, IF you plan on running the car hard on a road track for an extended time. Not sure why you feel forced to have cats in Texas. I've never had them look for cats.

[Joshinator99]

Originally Posted by soceur77

I'm going with a GESI Green cat distributed via Kooks.

This... only way to go if you want big power through cats IMO.

[mlee]

My HF cats didn't last.... and they tend to take out your O2 sensors when they go.

[waterman]

Originally Posted by mlee

At 800 you're will definitely want to ditch the cats, IF you plan on running the car hard on a road track for an extended time. Not sure why you feel forced to have cats in Texas. I've never had them look for cats.

Liberty is held in high regard in the Lone Star State. Those principles and a state government that allows their citizens and businesses prosper are a winning combination. Love me some Texas!


OP, secondary cats are a CARB requirement. Cats are restrictive, a second set of cats are VERY restrictive. They are only required in 12 (nanny)states and DC.

It's likely that ditching them could affect your warranty but will definitely increase flow and performance. Secondary cats are not monitored so losing them will not throw codes, unless you have a leak in the system. If you are tuning, that is of no concern as that voids your warranty anyway.

As soceur77 mentioned, GESI/high flow cats handle the heat (and federal emissions requirements) of high HP ratings well, without the need to run a rich (OEM) tune to keep them cool (as Rlhay2 noted).

[GT-ER]

Originally Posted by mlee

At 800 you're will definitely want to ditch the cats, IF you plan on running the car hard on a road track for an extended time. Not sure why you feel forced to have cats in Texas. I've never had them look for cats.

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.

[laynlo15]

I'm right at 800 rwhp on the new motor but I will only be drag racing mine so its not like I'm driving stop light to stop light. Tuning is critical if you are running cats since, to rich and you'll cook them pretty quickly

[GT-ER]

Originally Posted by mlee

My HF cats didn't last.... and they tend to take out your O2 sensors when they go.

Attachment 978722

Attachment 978723

Attachment 978724

What cats were those?

[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.

[GT-ER]

Well, I ended up purchasing two kook green cats, big bucks for some cats.. I love the sound and lack of smell with catted exhausts, but always worried about the power loss and longetivity. We'll see.

[SJFGTO]

Originally Posted by GT-ER

Well, I ended up purchasing two kook green cats, big bucks for some cats.. I love the sound and lack of smell with catted exhausts, but always worried about the power loss and longetivity. We'll see.

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.