Help Kooks Headers vs Corsa CB Exhaust

[Jfkayne]

Hi everyone,

New member to the forum. Just picked up my 24 blacking in Dec. Already have the itch to mod the exhaust. I have been listening to sound clips but its really hard to tell if I am better keeping the factory catback exhaust and then replace the headers with Kooks + green cats or if I am better off keeping the factory cats/headers and replacing the cat back system with Corsa. Couple of questions for anyone with experience.

• Better sound gains with headers or cat back exhaust if you had to pick one?
• Will the Kooks headers + green cats void the factory warranty and throw a CEL? Is a tune required?
• Will I need to cut the factory exhaust to install a Corsa system?

No other plans to modify the car for now so importance of header performance is not really that relevant but performance gains are always welcome.

Thanks in advance!

 

[Bigl]

Debating the same thing. I’d like to keep the factory exhaust because the tips looks so much cleaner than the Corsa exhaust but worried about passing NYS emissions testing

 

[blkout]

Well, if it helps, the Kooks will add 30whp, the Corsa catback will add none. Sound is a very subjective thing so no one can tell you what sounds best to your ears.

Kooks headers and green cats will likely void your warranty at most dealers, although its possible you might find one that won't blame an issue on them. A catback is far less likely to void your warranty.

You don't need to cut the factory exhaust to install a Corsa catback exhaust, but you will if you install a Corsa axle-back exhaust.

 

[Jfkayne]

Debating the same thing. I’d like to keep the factory exhaust because the tips looks so much cleaner than the Corsa exhaust but worried about passing NYS emissions testing

I also live in NY. If there is no CEL you will be fine. Does anyone know if the green cats require you to run a tune in order to avoid the CEL? If so I guess that would completely void the warranty.

 

[blkout]

I also live in NY. If there is no CEL you will be fine. Does anyone know if the green cats require you to run a tune in order to avoid the CEL? If so I guess that would completely void the warranty.

Many people have installed them without a CEL, I can't guarantee it though. Tune is not required.

 

[Jfkayne]

Well, if it helps, the Kooks will add 30whp, the Corsa catback will add none. Sound is a very subjective thing so no one can tell you what sounds best to your ears.

Kooks headers and green cats will likely void your warranty at most dealers, although its possible you might find one that won't blame an issue on them. A catback is far less likely to void your warranty.

You don't need to cut the factory exhaust to install a Corsa catback exhaust, but you will if you install a Corsa axle-back exhaust.

Is it 30whp with the green cats or is that just the competition pipes?

 

[blkout]

Is it 30whp with the green cats or is that just the competition pipes?

With green cats (high flow cats), there's almost no difference between a high flow cat and straight pipe other than cost. There's another member here that has Blackwing that makes over 1000whp, he removed his cats and gained about 8whp. That's nothing on a car that makes over 1000whp and most cars well under that power level aren't going to see any change at all.

 

[Jfkayne]

With green cats (high flow cats), there's almost no difference between a high flow cat and straight pipe other than cost. There's another member here that has Blackwing that makes over 1000whp, he removed his cats and gained about 8whp. That's nothing on a car that makes over 1000whp and most cars well under that power level aren't going to see any change at all.

Just to clarify... He removed the factory cats and picked up 8whp. Is that correct? If so that is more in-line with the gains I would expect. Picking up 30whp going from factory to green cats sounds like a lot.

 

[blkout]

Just to clarify... He removed the factory cats and picked up 8whp. Is that correct? If so that is more in-line with the gains I would expect. Picking up 30whp going from factory to green cats sounds like a lot.

You misunderstood. You would gain 30whp going with headers and high flow cats compared to the stock manifolds and stock cats. The guy that gained 8whp had over 1000whp so unless you plan to mod yours to that level, you would see almost nothing swapping out the high flow cats for off-road pipes.

 

[Jfkayne]

You misunderstood. You would gain 30whp going with headers and high flow cats compared to the stock manifolds and stock cats. The guy that gained 8whp had over 1000whp so unless you plan to mod yours to that level, you would see almost nothing swapping out the high flow cats for off-road pipes.

Wow way better than I thought. Thanks for the clarification

 

[blkout]

Wow way better than I thought. Thanks for the clarification

He gained 10whp going from high flow cats to off-road pipes but this was on a car that made over 1000whp. Here's the thread.

CT5-V Thread 'CT5 BW Ported 2650 - 1010WHP'

Mar 10, 2025

Hi all,

A few weeks ago I finished performance modding the 2023 CT5-V BW manual 6 speed to my liking (for now). Wanted to share my mod list and power #'s for others looking to go down this route.

Note: we are on a conservative tune and pulley setup; I didn't want to go more aggressive as I did not upgrade the bottom end when I started this journey. The car is running great, zero issues, as a daily. I'm considering an LTR long block so we can really spice it up as the next step (eventually).

Fuel: E85
Max WHP - 1010 @ 6,820 RPM
Max TQ - 873 @ 4,990 RPM

Shop: Omni Motorsports in...

• Blue
• Replies: 23
• Forum: Blackwing Mods/Tech/Performance

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[Jfkayne]

Can anyone out there speak to the sound difference between factory headers and an aftermarket CB exhaust vs aftermarket headers, green cats and a factory exhaust? I assume headers and green cats would be louder? I have listened to so many videos and honestly I really can’t hear that much of a difference with the CB exhaust but that might just be the video.

 

[Kawman]

A few of us are doing a group buy for ARH downpipes for our 4BW's. Join the group and get our discount.
Here's a link to their products for the 5BW. PM me if interested.

I just learned about cats while deciding on the ARH downpipes. The OEM cats are 800 cell, 400 cell is the least restrictive that gets EPA approval. Many of the products out there have lower prices because they use less expensive 300 cell cats. These cell numbers are the cells per inch. The Kooks green cats mentioned are EPA approved, so they must be 400 cell.

Cadillac CT5-V Blackwing Full System

CT5-V Blackwing owners, ARH has answered the call for horsepower and performance for your Blackwing! Now available are our 100% U.S. made long tube header 304 S/S full systems that are designed to fit great, install easily and produce outstanding horsepower and torque. This includes 3/8" thick...

americanracingheaders.com

 

[blkout]

Wow way better than I thought. Thanks for the clarification

I just realized you have a CT4 Blackwing so your power gains from headers are going to be a bit lower than what I quoted since I thought you had a CT5 Blackwing, my bad. You can probably expect 20whp from headers and high flow cats. I would reach out to @WONT TAP (Tapout Tuning) and get their opinion.