[PeteSS2018]

After reading a post on a different section of the forums, I've wondered whether I should go to high flow cats? Running a whipple & stock NPP exhaust. My concern is the blower pushing a lot of heat through cats that may damage the standard units, and also flow restrictions that they cause.

Here in Australia we arent allowed to remove cats, but can change them. So should I change? and if so is that primaries, secondaries or both? And will it need tuning for either?

[oldman]

A set of cat deletes pipes which remove all 4 cats, then weld in 2 high flow metal cats.... your golden

[Omega]

^Agreed. A set of loose cats like these would help



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[Joshinator99]

Originally Posted by Omega

^Agreed. A set of loose cats like these would help



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I wouldn’t use those. Cheap cats do not stand up to forced induction cars at all. The material to make strong cats is expensive, there is no way to make them cheap. The new Kooks Ultra Green Cats are great, and the Dynatech Powercats took a beating on my car and are still holding strong too.

[laynlo15]

How much power are you making. Gm did a good job on the exhaust including the cats on the Camaro. If your not changing to headers there is no reason in my opinion. I made 770 on the stock exhaust and ran 10.00@140 on the stock exhaust with the Magnuson 2300 on the bone stock Lt1. I wouldn't waste the money on them, the only big advantage is weight.

[oldman]

I'm on stock headers now, all 4 stock cats, front two are pretty heavily modified though. I've spend way to much time on it and I think my recommendation would be:
1)For engines upto 700 HP leave it stock or just mod the front two cats (one day I will do a write up). Or you could just CA front cat deletes and move the 02 behind the second cats.

2) all 4 cat delete pipes with weld in metal core cats upto 800 engine HP,

3) 2" headers coated with NO cats for engines above that.

[Herold Motorsports]

Originally Posted by laynlo15

How much power are you making. Gm did a good job on the exhaust including the cats on the Camaro. If your not changing to headers there is no reason in my opinion. I made 770 on the stock exhaust and ran 10.00@140 on the stock exhaust with the Magnuson 2300 on the bone stock Lt1. I wouldn't waste the money on them, the only big advantage is weight.

I wouldn't say its a waste of money. Theres more advantage than weight

Cats, even if working properly, are a restriction in the exhaust and do bring the power down. On simple builds not so much but the more you make and the more exhaust that is being pushed, the greater the loss of having cats will be. But I do agree that if youre not looking to get crazy with the set up, cats are fine. ZL1s have them, though theirs are a little more free flowing, and are doing crazy with stock exhaust set ups.

But for the money, a nice set of headers with high flow or catless mids is well worth it.

Efficiency makes power. If youre bringing in a lot more air (forced induction) and limiting how much air can get out by having factory exhaust, then you are leaving power on the table. More air in, more air out.

[Joshinator99]

Originally Posted by Spencer@DarkNight

I wouldn't say its a waste of money. Theres more advantage than weight

Cats, even if working properly, are a restriction in the exhaust and do bring the power down. On simple builds not so much but the more you make and the more exhaust that is being pushed, the greater the loss of having cats will be. But I do agree that if youre not looking to get crazy with the set up, cats are fine. ZL1s have them, though theirs are a little more free flowing, and are doing crazy with stock exhaust set ups.

But for the money, a nice set of headers with high flow or catless mids is well worth it.

Efficiency makes power. If youre bringing in a lot more air (forced induction) and limiting how much air can get out by having factory exhaust, then you are leaving power on the table. More air in, more air out.

Agreed. With just a Whipple last year, secondary cat delete, a couple of bolt ons and a safe tune (.82 lambda, ~650 WHP), my primary cats were scorching hot (over 1600 degrees) by the end of my 1/4 mile run. So I’d say by 650-700 WHP they are really screaming and definitely a restriction IMO. Just my 2 cents of course.