Need help to quiet down LT headers w/ Corsa catback

hardcore-gm · May 10, 2021

Hey guys just looking for some good and informed opinions on quieting down the exhaust. 14 Sierra 6.2 with Kooks LT headers and y pipe with hi flow cats. Thats connected to Corsa sport catback. Sounds great but just too much at cold start, its too wicked. I'm hoping now to get maybe half the sound at least on cold start. Anybody have experience with this and doing some trial and error? Maybe even just putting stock muffler on catback on? Or i saw something about just adding a muffler before the Corsa, or just swapping the corsa muffler out with a magnaflow.. maybe 12909? any feedback would be appreciated!! Dont wana sell this nice setup but might have to if theres no good options. thanks!

scrapen · May 10, 2021

Adding a Vibrant resonator just ahead of the muffler will fix it for you. If you have a CC it fits just fine. I can’t speak for SC and DC trucks.

langston1726 · May 10, 2021

On 5/10/2021 at 3:30 PM, hardcore-gm said:

Hey guys just looking for some good and informed opinions on quieting down the exhaust. 14 Sierra 6.2 with Kooks LT headers and y pipe with hi flow cats. Thats connected to Corsa sport catback. Sounds great but just too much at cold start, its too wicked. I'm hoping now to get maybe half the sound at least on cold start. Anybody have experience with this and doing some trial and error? Maybe even just putting stock muffler on catback on? Or i saw something about just adding a muffler before the Corsa, or just swapping the corsa muffler out with a magnaflow.. maybe 12909? any feedback would be appreciated!! Dont wana sell this nice setup but might have to if theres no good options. thanks!

A resonator or smaller muffler in front or back will definitely help take the edge off if you don’t mind cutting up the Corsa system. I ran several different resonators/mufflers with a Borla Atak crate muffler and TSP longtubes including an oval Borla XR1. The Atak was way to loud by itself and had a cackle sound I didn’t care for. I ended up selling the Atak muffler and just ran the Xr1. Still sounds like the truck has headers but not obnoxiously loud on start up. It will definitely still get loud when I want it to be. A big Magnaflow should make it significantly quieter. Hard to beat that Corsa sound though. Just a tamed version of it would be nice.

Edited May 20, 2021 by langston1726

lucas287 · May 10, 2021

Are you customed tuned? There's a setting that takes 5 seconds to change that will make cold starts much nicer. I, too, have a Corsa catback (no headers) and I used my HPTuners software to tame it down.

Basically what happens is the timing gets really low, actually negative, in order to get heat further down into the manifolds/cats to warm them up quicker. It only lasts maybe 30 seconds but that combined with high startup rpm can get annoying.

Edited May 10, 2021 by lucas287

langston1726 · May 11, 2021

2 hours ago, lucas287 said:

Are you customed tuned? There's a setting that takes 5 seconds to change that will make cold starts much nicer. I, too, have a Corsa catback (no headers) and I used my HPTuners software to tame it down.

Basically what happens is the timing gets really low, actually negative, in order to get heat further down into the manifolds/cats to warm them up quicker. It only lasts maybe 30 seconds but that combined with high startup rpm can get annoying.

My tune definitely helped with taming the cold starts down. What’s strange with mine though is when it is 40 deg or colder out, mine will actually start as if the truck is already warm. If it’s any warmer it will go thru a cold cycle. I had Blackbear take a look at the tune he didn’t find anything out of the ordinary. Just seems counterintuitive of a “cold start”.

lucas287 · May 11, 2021

12 minutes ago, langston1726 said:

My tune definitely helped with taming the cold starts down. What’s strange with mine though is when it is 40 deg or colder out, mine will actually start as if the truck is already warm. If it’s any warmer it will go thru a cold cycle. I had Blackbear take a look at the tune he didn’t find anything out of the ordinary. Just seems counterintuitive of a “cold start”.

Yep, that's exactly what that mode does. It has a window that its active in, I forget the range. But true "cold" starts it wont do it. When its mild out, it'll happen though. It's based on coolant temp. Ask Justin about disabling the exhaust catalyst warmup mode. I can find it in HPTuners but he uses EFI Live anyway.

langston1726 · May 11, 2021

3 minutes ago, lucas287 said:

Yep, that's exactly what that mode does. It has a window that its active in, I forget the range. But true "cold" starts it wont do it. When its mild out, it'll happen though. It's based on coolant temp. Ask Justin about disabling the exhaust catalyst warmup mode. I can find it in HPTuners but he uses EFI Live anyway.

Good to know. I’m okay with it as long as it’s not hurting anything. I don’t mind the cold starts either but wondered if maybe I had a faulty temp sensor somewhere. Thanks for the info.

hardcore-gm · May 12, 2021

Gotcha thanks guys! I might have to look into the vibrant resonator.. il proly have a hard time deciding between a magnaflow and the resonator tho might just ask the shop guys wat they think.

hardcore-gm · May 12, 2021

Btw anyone know the difference between the bottle style and the ultra quiet resonators?

CamGTP · May 12, 2021

The bottle style does less than the ultra quiet because of the design and size of the resonator.

KONGon22s · May 13, 2021

Wondering the same thing as OP but where on the CORSA system does a resonator fit? The elbow before the tip a small one one maybe...

lucas287 · May 13, 2021

I'd put it in between the flex pipe and the muffler!

JONBLARC7 · May 13, 2021

I have the 12909 with headers and catless y pipe. It will tame it down. BUT with my cam I've been wanting more to hear the cam better at idle, So I've had a XR1 sitting in my closet since Christmas. I just haven't had time to get it put on. The 12909 is a good muffler and pretty loud at WOT. But if you heard you truck with stock manifolds and muffler then just switched out the muffler to a 12909. It's no louder than the stock muffler, just deeper. It wasn't until I put the headers on my truck that it came alive.

In fact my wife even said you spent money on that muffler because she couldn't hear it crank from inside our house. But I knew I was putting headers on it soon. Since I already had a cam and I didn't want to rattle the neighbor's window. I'm ready to rattle windows now.

Lucas287 is right about the tune. I thought it was call split timing or something. But I could be completely wrong. I read about it on the HP forum. And paln to do that to my tune once I get the XR1 installed

hardcore-gm · May 13, 2021

10 minutes ago, JONBLARC7 said:

I have the 12909 with headers and catless y pipe. It will tame it down. BUT with my cam I've been wanting more to hear the cam better at idle, So I've had a XR1 sitting in my closet since Christmas. I just haven't had time to get it put on. The 12909 is a good muffler and pretty loud at WOT. But if you heard you truck with stock manifolds and muffler then just switched out the muffler to a 12909. It's no louder than the stock muffler, just deeper. It wasn't until I put the headers on my truck that it came alive.

In fact my wife even said you spent money on that muffler because she couldn't hear it crank from inside our house. But I knew I was putting headers on it soon. Since I already had a cam and I didn't want to rattle the neighbor's window. I'm ready to rattle windows now.

Lucas287 is right about the tune. I thought it was call split timing or something. But I could be completely wrong. I read about it on the HP forum. And paln to do that to my tune once I get the XR1 installed

thanks Jon for the input! Man would love to hear those cams on your truck.. so you would recommend going with 12909 over a resonator? Im sure the muffler would bring the tone deeper but how about total sound at cold start and idle?

JONBLARC7 · May 13, 2021

I'll up load another video to YouTube tonight of it after I have played with the overunder speed in the tune to get more chop. The TSP 218/226 is a great cam for the L86. But with a quiet exhaust is barely noticable at idle.

I have ran the 12909 on two 6.2's my 2008 denali full headers and catless and the L86 headers and catless. And like it on both, the only reason I'm changing it now it to hear my cam better. If i didnt have a cam I wouldn't change a thing.

Edited May 13, 2021 by JONBLARC7