lakemg

Long tube headers and high flow cats did the trick for me...

JerryU

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.

Foosh

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."

C6 MoneyPit

I think you are right on all counts. No way will they see it on a visual, they never even look underneath at the "check only" smog place I go and even if they did with the tunnel plate there it would be very hard to see. I have my doubts about the sniffer test as well so I plan to take it off before my next smog test is due in 4 years - I don't think it would pass but I don't know anyone who has tried yet.

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

fugly1

In 2015-, valves are open under a wider range of conditions with track rather than sport exhaust mode, no?

Foosh

I don't think so.

Eff A Ford

I did a muffler delete. Sounds great IMO.

A lot of people that did the Corsa or Borla axle-back did not notice much improvement over the stock NPP.

fugly1

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....

Foosh

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.

Munchen100

How many miles do you have on your car? Maybe it's my imagination, but my 2016 C7 exhaust seemed to "pop" more after about 3,800 miles.

fugly1

In addition to the owner's manual implying a distinction (though not specifying what it is), the "engine sound management" menu in the car does, as well. Options are "stealth", "tour", "sport" and "track". It could be that there is a difference between all of them except for "sport" and "track", but that would be very odd.

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.

Foosh

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."

fugly1

Not quite, but that's ok.

Still wondering what the difference between track and sport exhaust mode is....

Foosh

If a tree falls in a forest, and no one is there to hear it, is there still a noise?

fugly1

How about: Just because you don't know the answer to a question, does that mean the question doesn't matter?

Foosh

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.

owc6

OK, boys,

Just install some Bullets for some LOUD exhaust.

Foosh

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.

mountainears

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.

fugly1

So, looks like the answers to the questions posed in posts #25 and #35 are "yes".