Exhaust note
E-Ray, 3LZ, ZER, LIFT
Joined: Sep 2007
Posts: 35,018
Likes: 12,399
From: NE South Carolina
I can relate to the OP. Removed the secondary CATS via the Corsa double helix x-pipe and it made it noticeably better with the fuse pulled. I am not worried about any warranty issues as it would have to be shown that a defect or failure was related to removal of the secondary cats which would be a stretch IMO.
Believe you would be successful if warranty issue was raised by the dealer.In CA it would also be hard for them to see the CATs removed except if you had a Zellet "tree huger" who knew Vettes! They are "mostly" cover by sheet metal, as I recall. But you'all can't make any non approved changes to the engine/exhaust. Removing the secondary CATs is certainly NOT approved.
Wonder if you'll still meet the tight CA restrictions with the sniffers they use? In SC we have no emissions testing in our part of the State so no issue.
If a "better sound" was that important to me would not get NPP and buy Borla Mufflers. However on my GS on order-no choice, comes with the package.
Team Owner
Joined: Oct 2004
Posts: 25,583
Likes: 16,942
On a '14 if you select "mode dependent," valves are closed in Weather, Eco, and Tour, and open in Sport and Track. On later model years, you can, for example, select "Track" in Tour or any other mode, but on a '14 if you wanted to do that you'd just select "Off."
Last edited by Foosh; Feb 24, 2017 at 01:20 PM.
Melting Slicks
Joined: Feb 2006
Posts: 2,574
Likes: 136
From: Simi Valley California
St. Jude Donor '06-'07-'10, '15. '22-'23
Believe you would be successful if warranty issue was raised by the dealer.In CA it would also be hard for them to see the CATs removed except if you had a Zellet "tree huger" who knew Vettes! They are "mostly" cover by sheet metal, as I recall. But you'all can't make any non approved changes to the engine/exhaust. Removing the secondary CATs is certainly NOT approved.
Wonder if you'll still meet the tight CA restrictions with the sniffers they use? In SC we have no emissions testing in our part of the State so no issue.
If a "better sound" was that important to me would not get NPP and buy Borla Mufflers. However on my GS on order-no choice, comes with the package.
I also agree with you about the hindsight on the NPP. If I had it to do over I would have skipped it and gone right to a aftermarket Cat-back or muffler delete. I really miss the sound of my C6 by comparison! I used to downshift to every stop just to hear that burble and pop and my wife just looked at me like I was crazy - while I giggled every time LOL
Burning Brakes
Joined: Jan 2016
Posts: 782
Likes: 264
From: San Diego
Yes, there are only two actual settings for all MYs, "open" and "closed." You can call them whatever you want, but that's the only thing NPP does.
On a '14 if you select "mode dependent," valves are closed in Weather, Eco, and Tour, and open in Sport and Track. On later model years, you can, for example, select "Track" in Tour or any other mode, but on a '14 if you wanted to do that you'd just select "Off."
On a '14 if you select "mode dependent," valves are closed in Weather, Eco, and Tour, and open in Sport and Track. On later model years, you can, for example, select "Track" in Tour or any other mode, but on a '14 if you wanted to do that you'd just select "Off."
Burning Brakes
Joined: Jan 2016
Posts: 782
Likes: 264
From: San Diego
In the 2016 owner's manual, for exhaust mode, it says "sport" for sport mode and "track" for track mode, implying that there is a difference. I haven't yet found what that difference is, though.
Edit: Can't get the table to show...but it's as I described....
Edit: Can't get the table to show...but it's as I described....
Last edited by fugly1; Feb 24, 2017 at 07:13 PM. Reason: added table
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Team Owner
Joined: Oct 2004
Posts: 25,583
Likes: 16,942
Yes, I'm aware of that menu selection and "implying" is the key word in your post. In actuality, if there is any difference at all, it's essentially undetectable. Do you think you hear a difference between your "Sport" and "Track" NPP settings? Maybe it's just an "alternative fact."
Even with the fuse pulled, where the valves are most definitely open all the time, the difference is subtle between that and Sport/Track OEM settings. The main difference I discern is that with the fuse pulled, there is a slight drone at below 2K rpm cruise settings.
Even with the fuse pulled, where the valves are most definitely open all the time, the difference is subtle between that and Sport/Track OEM settings. The main difference I discern is that with the fuse pulled, there is a slight drone at below 2K rpm cruise settings.
Last edited by Foosh; Feb 24, 2017 at 08:15 PM.
Burning Brakes
Joined: Jan 2016
Posts: 782
Likes: 264
From: San Diego
Yes, I'm aware of that menu selection and "implying" is the key word in your post. In actuality, if there is any difference at all, it's essentially undetectable. Do you think you hear a difference between your "Sport" and "Track" NPP settings? Maybe it's just an "alternative fact."
Having said that, I took the car on a 2 mile trip this evening to pick up dinner and tried to hear the difference between sport and track. I couldn't. I'm guessing, though, that the difference is when the valves open up -- e.g., that the valves open up at a lower rpm in track than in sport.
Team Owner
Joined: Oct 2004
Posts: 25,583
Likes: 16,942
OK. You couldn't tell a difference. I can't either. That's been my one and only point from the beginning of this thread.
It probably looks better to people on the settings menu though. It makes the car look more "high-tech."
It probably looks better to people on the settings menu though. It makes the car look more "high-tech."
Last edited by Foosh; Feb 24, 2017 at 11:00 PM.
Burning Brakes
Joined: Jan 2016
Posts: 782
Likes: 264
From: San Diego
Still wondering what the difference between track and sport exhaust mode is....
Team Owner
Joined: Oct 2004
Posts: 25,583
Likes: 16,942
Perhaps you can just embrace the possibility that there is no difference. I don't see hoards of forum members rushing forward to suggest there is. Most people who want max noise just pull the fuse and forget about it, but you seem rather obsessed by a rather meaningless question considering you yourself can't tell any difference.
Over and out.
Over and out.
Team Owner
Joined: Oct 2004
Posts: 25,583
Likes: 16,942
Thanks for showing up, Lisa.
Bullets sound great, but there are times I like quiet. I'm good with NPP w/ the fuse pulled and installed the M2W device to make it quiet with a single button press on those few occasions where solitude is preferable on long cruises. The factory menu is rather cumbersome and silly with multiple button presses required to change the menu to what you'd like it to do.
Bullets sound great, but there are times I like quiet. I'm good with NPP w/ the fuse pulled and installed the M2W device to make it quiet with a single button press on those few occasions where solitude is preferable on long cruises. The factory menu is rather cumbersome and silly with multiple button presses required to change the menu to what you'd like it to do.
Last edited by Foosh; Feb 24, 2017 at 11:38 PM.
Melting Slicks
Joined: Jan 2017
Posts: 2,982
Likes: 1,040
From: Georgetown CA
2018 Corvette of Year Finalist
2017 C7 of Year Finalist
Refer to this thread that XP800 started, to me is one of the key references on NPP in this forum. https://www.corvetteforum.com/forums...ck-result.html
Point #5 in particular, which I think addresses the question at hand, what is the difference between the various exhaust modes. As noted by most, it is arguable something that is not noticed by most, because it as he describes it (assuming it is accurate) it is about how aggressively the valves open and close (opening earlier and longer). So people should not expect a huge difference, and the best you can do is to pull the fuse.
The stuff that XP800 has written about it in a few threads should be combined into a sticky IMHO.
Point #5 in particular, which I think addresses the question at hand, what is the difference between the various exhaust modes. As noted by most, it is arguable something that is not noticed by most, because it as he describes it (assuming it is accurate) it is about how aggressively the valves open and close (opening earlier and longer). So people should not expect a huge difference, and the best you can do is to pull the fuse.
The stuff that XP800 has written about it in a few threads should be combined into a sticky IMHO.