C7 LT1 Rapsy Exhaust Solutions
Thread Starter
Melting Slicks
Joined: Feb 2010
Posts: 3,330
Likes: 903
From: Kentucky
C7 LT1 Rapsy Exhaust Solutions
A few months ago, I installed catless headers and x pipe into stock NPP on my Z51. Also added a flex fuel sensor and the power bump is nice. I love the sound at some points in the rpm range but not in others. I guess I didn't realize how much more raspy the LT1 motor is over the LS3 I had before this. I'm looking at options to deepen the sound. I've thought about adding high flow cats, swapping the x pipe for a custom H pipe, or sticking some resonators somewhere in the setup. Anyone else have experience with this?
Advanced
Joined: Mar 2022
Posts: 79
Likes: 81
From: The Bay, CA
I posted a similar thread to this a while back and I assumed resonators would be the answer but the info I gathered there was that resonators were not the solution. The best answer I got was to use 1 or even 2 of these: https://www.summitracing.com/parts/sih-94410
I have not added them to my car yet so I can't attest to how they'll sound but they do seem promising based of YouTube videos.
I have not added them to my car yet so I can't attest to how they'll sound but they do seem promising based of YouTube videos.
Last edited by Neorift; Apr 1, 2026 at 07:59 PM.
Thread Starter
Melting Slicks
Joined: Feb 2010
Posts: 3,330
Likes: 903
From: Kentucky
I've ordered these and they're going on the car on Tuesday. I'll post my opinion here. I've never actually heard of these but apparently they act as a sort of resonator.
https://www.speedwaymotors.com/Dynat...nch,48598.html
https://www.speedwaymotors.com/Dynat...nch,48598.html
Melting Slicks
Joined: May 2013
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From: New Jersey
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I agree with trying high-flow cats.
Advanced
Joined: Mar 2022
Posts: 79
Likes: 81
From: The Bay, CA
I've ordered these and they're going on the car on Tuesday. I'll post my opinion here. I've never actually heard of these but apparently they act as a sort of resonator.
https://www.speedwaymotors.com/Dynat...nch,48598.html
https://www.speedwaymotors.com/Dynat...nch,48598.html
Thread Starter
Melting Slicks
Joined: Feb 2010
Posts: 3,330
Likes: 903
From: Kentucky
To the suggestions for high flow cats - yeah that would probably fix my issue but I’m already tuned and I’d hate to spend the money on another tune if I don’t have to. If these resonators don’t work, I’ll probably go that route.
Le Mans Master
Joined: Jun 2016
Posts: 5,456
Likes: 4,016
From: Cincinnati, OH
They can be wherever you want them. I’m probably going to do in the front of the X pipe, before the X
To the suggestions for high flow cats - yeah that would probably fix my issue but I’m already tuned and I’d hate to spend the money on another tune if I don’t have to. If these resonators don’t work, I’ll probably go that route.
To the suggestions for high flow cats - yeah that would probably fix my issue but I’m already tuned and I’d hate to spend the money on another tune if I don’t have to. If these resonators don’t work, I’ll probably go that route.
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Thread Starter
Melting Slicks
Joined: Feb 2010
Posts: 3,330
Likes: 903
From: Kentucky
Update: the exhaust shop installed them in the rear of the x pipe, as close to the x as they could without slicing things up. The result is honestly pretty impressive. It almost completely eliminated the raspy, teeny noises while still maintaining the overall sound level I wanted. Startup in Sport is noticeably deeper and although I lost a few decibels at WOT, the overall sound is also deeper. Really pleased with how it turned out, especially for the price.
Le Mans Master
Joined: Jun 2016
Posts: 5,456
Likes: 4,016
From: Cincinnati, OH
Update: the exhaust shop installed them in the rear of the x pipe, as close to the x as they could without slicing things up. The result is honestly pretty impressive. It almost completely eliminated the raspy, teeny noises while still maintaining the overall sound level I wanted. Startup in Sport is noticeably deeper and although I lost a few decibels at WOT, the overall sound is also deeper. Really pleased with how it turned out, especially for the price.
Thread Starter
Melting Slicks
Joined: Feb 2010
Posts: 3,330
Likes: 903
From: Kentucky