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Looking for suggestions on headers. I have always liked kooks but heard they aren't that great with the C8 and that you actually lose HP with stock cats. Was also looking at American Racing and AFE. Any suggestions?
Looking for suggestions on headers. I have always liked kooks but heard they aren't that great with the C8 and that you actually lose HP with stock cats. Was also looking at American Racing and AFE. Any suggestions?
I'll be honest with you and say what some wont...
So we have had cars with ARH pick up HP and some didn't pick up much at all. Same with Kooks, AFE and the other big names making them. (Not a knock on any companies product by any means)
Since the factory ECU isn't unlocked there is no was to tune a c8 to maximize the gains from bolt on upgrades, Also its worth mentioning that unlike previous generations of corvettes the cats are not located in the headers so installing aftermarket headers doesn't include a cat delete so the performance gains will be minimal. We have made 1100whp through the factory headers on a built engine TT car so its apparent they flow pretty well.
When it comes to sound I do feel the headers give the car a more exotic sound higher in the RPM band and I personally feel it makes the experience of driving the car better regardless of performance gains.
If power is your main objective then the biggest exhaust upgrade is sport cats for sure and they will amplify the sound as well. Lots of good options out there for sport cats (including ours haha)
I would be more than happy to answer any questions you have about mods for the C8, we have tested quite a few of them haha.
I have AFE on my car. Both AFE & ARH are CARB-approved for what it's worth. CARB aside, these are the only two quality brands with proven power increase that I'd consider on my personal car. Avoid the Kooks or anyone rebranding Kooks (Lingenfelter, Corsa, etc.) due to the flange restriction, as you mentioned.
Regarding AFE vs. ARH it really depends what you want from the car. Nice fat mid-range with gains right off idle or minimal to no gains below 4k RPM with a stronger top-end? Also, when comparing dyno charts, watch the RPM along X-axis as some can be skewed to mislead the powerband and where the gains are located.
AFE has a 2.75" outlet flange which matches perfectly with stock or Corsa cats. ARH had a 2.875" outlet flange so if you add high-flow cats it would be ideal to get a set with a full 3" inlet (Cicio & Fabspeed come to mind).
AFE includes all GM Genuine gaskets while ARH includes generic style aftermarket gaskets. Some people likely don't care but for long-term reliability and durability, this was important to me.
Ask away if you have any other questions, I'm sure there's plenty I'm forgetting! Scroll down a bit in this section and you'll find my thread with pictures and install notes.
Looking for suggestions on headers. I have always liked kooks but heard they aren't that great with the C8 and that you actually lose HP with stock cats. Was also looking at American Racing and AFE. Any suggestions?
I'll be honest with you and say what some wont...
So we have had cars with ARH pick up HP and some didn't pick up much at all. Same with Kooks, AFE and the other big names making them. (Not a knock on any companies product by any means)
Since the factory ECU isn't unlocked there is no was to tune a c8 to maximize the gains from bolt on upgrades, Also its worth mentioning that unlike previous generations of corvettes the cats are not located in the headers so installing aftermarket headers doesn't include a cat delete so the performance gains will be minimal. We have made 1100whp through the factory headers on a built engine TT car so its apparent they flow pretty well.
When it comes to sound I do feel the headers give the car a more exotic sound higher in the RPM band and I personally feel it makes the experience of driving the car better regardless of performance gains.
If power is your main objective then the biggest exhaust upgrade is sport cats for sure and they will amplify the sound as well. Lots of good options out there for sport cats (including ours haha)
I would be more than happy to answer any questions you have about mods for the C8, we have tested quite a few of them haha.
Regarding sport cats... I can go down a deep rabbit hole here but I'll try to keep in short. You have to be very careful on which ones to get in order to ensure you don't get a check engine light. Kooks, Cicio, Paragon, & Corsa all use similar quality GESi G-Sport GEN2 S-Wound 400-cell cores. Fabspeed & Soul both use HJS 200-cell cores. Any of these options are about as good as it gets. GESi are made in North America while HJS are German. I personally opted for Corsa on my car. Note that I wouldn't pair the Kooks cats with anything but Kooks headers due to the smaller flange size.
If I have to nitpick, Paragon uses a smaller diameter core which isn't going to flow as well as the rest. Cicio's inlet flange doesn't retain the OEM style gasket. This is what eliminated both of these during my decision making process. Both relatively small issues, but I had whittle down the various options some how.
Regarding sport cats... I can go down a deep rabbit hole here but I'll try to keep in short. You have to be very careful on which ones to get in order to ensure you don't get a check engine light. Kooks, Cicio, Paragon, & Corsa all use similar quality GESi G-Sport GEN2 S-Wound 400-cell cores. Fabspeed & Soul both use HJS 200-cell cores. Any of these options are about as good as it gets. GESi are made in North America while HJS are German. I personally opted for Corsa on my car. Note that I wouldn't pair the Kooks cats with anything but Kooks headers due to the smaller flange size.
If I have to nitpick, Paragon uses a smaller diameter core which isn't going to flow as well as the rest. Cicio's inlet flange doesn't retain the OEM style gasket. This is what eliminated both of these during my decision making process. Both relatively small issues, but I had whittle down the various options some how.
Ya you aren't lying on the cel issue, we worked hard to make sure they don't pop up.
I just feel from what we have seen from the cars that the sport cats are a better "performance" upgrade as opposed to the headers.
So we have had cars with ARH pick up HP and some didn't pick up much at all. Same with Kooks, AFE and the other big names making them. (Not a knock on any companies product by any means)
Since the factory ECU isn't unlocked there is no was to tune a c8 to maximize the gains from bolt on upgrades, Also its worth mentioning that unlike previous generations of corvettes the cats are not located in the headers so installing aftermarket headers doesn't include a cat delete so the performance gains will be minimal. We have made 1100whp through the factory headers on a built engine TT car so its apparent they flow pretty well.
When it comes to sound I do feel the headers give the car a more exotic sound higher in the RPM band and I personally feel it makes the experience of driving the car better regardless of performance gains.
If power is your main objective then the biggest exhaust upgrade is sport cats for sure and they will amplify the sound as well. Lots of good options out there for sport cats (including ours haha)
I would be more than happy to answer any questions you have about mods for the C8, we have tested quite a few of them haha.
Thanks
Andrew
Very interesting, I’ve read over the past couple years that it’s the other way around. Where Sport Cats make little performance gains (1-3hp) while headers make up to 15hp gains. But I’ll take your word since I bet you have real-world examples to back up your claim.
I have 200cell cats (brand: 2M) to be installed onto my stock headers in the next couple weeks so this is good to know! Mainly purchased for sound, but some extra ponies don’t hurt
Cats also reduce decent amount weight if you’re into that. Every bit counts. Especially off the rear of the car.
Looks like sport cats save roughly 12 lbs and I think headers are about the same, not a bad way to pick up a few ponies and shed 20-25 lbs at the same time.
Very interesting, I’ve read over the past couple years that it’s the other way around. Where Sport Cats make little performance gains (1-3hp) while headers make up to 15hp gains. But I’ll take your word since I bet you have real-world examples to back up your claim.
I have 200cell cats (brand: 2M) to be installed onto my stock headers in the next couple weeks so this is good to know! Mainly purchased for sound, but some extra ponies don’t hurt
Im not saying we haven't had cars pick up some hp when adding headers but it has never been anything super substantial.
The most restrictive part of the factory exhaust is definitely the catalytic converters so going to a higher flowing unit will have the greatest affect on exhaust flow.
We haven't personally tried the 2M cats yet so ill be interested to see your results, I have a feeling it will help and I know for a fact it will increase the sound as well.
Im not saying we haven't had cars pick up some hp when adding headers but it has never been anything super substantial.
The most restrictive part of the factory exhaust is definitely the catalytic converters so going to a higher flowing unit will have the greatest affect on exhaust flow.
We haven't personally tried the 2M cats yet so ill be interested to see your results, I have a feeling it will help and I know for a fact it will increase the sound as well.
I went with ARH. They are very well made, quality part. However......the OEM headers are a work of art. Tons of time and effort went into developing them, and I doubt the aftermarket long tubes can compete performance wise.
If I could go back, I wouldn't swap them out, and I may revert back in the future at some point.
The best part about the factory headers is that flange at the head and the heat insulation & shielding. I'm not sure I'd call them a work of art, but the GM engineers clearly did their homework and made great header as far as mass-produced OEM parts go. Same with the factory intake/airbox/filter design.
I saw zero performance increase from the headers. Probably more pain than its worth, the factory heat shielding on the stock headers is a work of art.
If i could go back..... haha..... i will continue walking down the path I am though.
Just curious .....what headers did you have? I saw two disappointments with the kooks headers....dyno and drag strip. Sounds like kooks didn't get it right with the C8 and still just threw their product out there. And we are talking about a very reputable company with their products.
IAlso its worth mentioning that unlike previous generations of corvettes the cats are not located in the headers so installing
Since when were cats located *in* the headers on corvettes? This has never been the case in at least c5-c8 corvettes to my knowledge. Don't know about earlier than that but c5-c8 the cats have all been separate from the headers.
Since when were cats located *in* the headers on corvettes? This has never been the case in at least c5-c8 corvettes to my knowledge. Don't know about earlier than that but c5-c8 the cats have all been separate from the headers.
I think he was referring to long tube headers replacing the cats at the same time as replacing the cast iron exhaust manifolds. Just a guess on my part. I'm actually glad nobody is doing it like that [yet] on the C8 and keeping things modular so we can each piece our own individual systems together as we best see fit (plus, keeps things emissions-friendly for those that need it - I bet this is honestly the main driver here).
So we have had cars with ARH pick up HP and some didn't pick up much at all. Same with Kooks, AFE and the other big names making them. (Not a knock on any companies product by any means)
Since the factory ECU isn't unlocked there is no was to tune a c8 to maximize the gains from bolt on upgrades, Also its worth mentioning that unlike previous generations of corvettes the cats are not located in the headers so installing aftermarket headers doesn't include a cat delete so the performance gains will be minimal. We have made 1100whp through the factory headers on a built engine TT car so its apparent they flow pretty well.
When it comes to sound I do feel the headers give the car a more exotic sound higher in the RPM band and I personally feel it makes the experience of driving the car better regardless of performance gains.
If power is your main objective then the biggest exhaust upgrade is sport cats for sure and they will amplify the sound as well. Lots of good options out there for sport cats (including ours haha)
I would be more than happy to answer any questions you have about mods for the C8, we have tested quite a few of them haha.
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C8 Headers
