I'm very unhappy with the way this car sounds, even with "My Mode" in "Track" exhaust at all times. I have plans for a catback exhaust but don't have the money right now and the car is just sitting because I have no desire to drive it.

I've heard a fuse pull mentioned for the NPP valves. I did something on my Hellcat that is probably similar - pull the fuse for active exhaust valves while the car is warming up during a cold start when they are in "full open" position. I don't believe this threw a CEL.

1. Is there a significant improvement in sound?
2. Does this throw a CEL? Is there any way around that so I don't have one?
3. Is there any guide for doing this? This question is only relevant if the answer is "yes" to the above two questions.

 

I have a mild to wild switch for sale in the classified section if your interested. so you don't have to pull fuses.

 

It’s my understanding that the mild to wild will not work on the c8

 

This is why C8 exhaust systems sell like hotcakes vs. C7 sales!

 

A fuse pull will throw a code. All indications are that the Mild2Wild doesn't work on the C8. With the exhaust in track mode, the valves are open almost all the time anyway. If a fuse pull worked, it wouldn't make the car any louder. (It sounds plenty loud outside the car, btw.)

The C8 Stingray exhaust sounds weak inside the car because the exhaust tips are further away from you than in prior 'vettes, and because there's a giant lump of V8 in between you and the exhaust. And in the coupe, a really thick piece of glass.

The only practical way to make the exhaust louder inside the car is a catback, or sport cats, or headers (or a combination). But that will make it MUCH louder outside the car.

 

Track mode , Z mode, My mode, doesn't matter the valves still close around 2k rpm's when cruising I've got data log videos to prove it. The only way to keep them open all the time is unhook the NPP valve when open and put on a simulator. I have simulators for $75 a pair.

 

With the engine/sound set to Track or Sport, the valves are open almost all the time. It is true that they close at certain times with low acceleration and RPM to meet Federal Bypass Standards. The question is, if force open all the time will there be any perceived difference worth the effort. Someone in the thread at the link below tried that, and decided it did not make much, if any difference. You can skip to his conclusion in post 24, or read the whole thread.

https://www.corvetteforum.com/forums...ispreloading=1

 

Thanks for the information. I'm too poor for Borla/Corsa variable to keep NPP anyway so the plan is to save up for something loud and delete NPP and AFM. People are saying lack of AFM valves makes the car sound terrible in V4 mode. However, this only occurs on the highway when cruising, and you can use manual mode to prevent V4 mode. I've had obnoxiously loud cars my whole life and I doubt it's going to bother me.

If I'm still in the market when I get the catback I'll give your ad a look.

 

I have a base car that didn't have the NPP exhaust. I added it and the valves don't work as the car isn't wired for it. That said, I run it in loud mode all the time,,, BTW it isn't that loud. You don't need to disconnect the NPP actuators and add simulators, wasted money. Get longer bolts and spacers/washers so the actuators don't engage. The flaps normally stay open without the actuators.

 

So this is false advertising

 

Some have said that. I don't think you will find a post where I said that. They even show a video of working. What I have said is the even it if it works, the difference in sound between running with engine sound set to Track and forcing the valves open all the time is not much if any from a perception point of view. The valves do close (around 2 k when cruising according to post above) to meet Federal Bypass Standards, and they do close in AFM mode. This is the thread where a person forced the valves open all the time - and concluded it was not worth the effort.
https://www.corvetteforum.com/forums...ispreloading=1

 

Deceptive advertising at best. Notice they don't claim that it won't cause a CEL but I think everything they say is true. I.e., it probably does stop the NPP valves from closing. And perhaps the CEL clears itself after driving a while with the valves operating normally.

If they have a good return policy someone might try again and see if they can get it to work without a CEL (or live with the CEL if you don't care). My bet is it throws a CEL when used.

 

3M cat deletes only

 

Sugey, My son lives in St Lucie, next time I'm down there I'll look you up so I can hear in person.

 

Search the C8 General forum for Mild2Wild and you'll find many, many posts from people who tried it and say it doesn't work.

 

Sold the C8 Stingray now have C8 Z06. No worries though cat deletes are going on this one too 😎

 

@mortelec 's post above contradicts that the valves stay open most of the time, and to be honest the sound I hear while accelerating at anything but WOT is not what I expect to hear as a higher-rpm version of what I hear at cold start. However everyone seems to agree that a MIL is unavoidable, so I've given up on this prospect. I disagree with you about it being plenty loud, coming from multiple other modern muscle cars with full exhaust systems and missing all of them right now.

The second part of your post had made me feel stupid for a few days now. I didn't realize that was part of the problem; the fact that there's so much metal makes me unable to hear my own car. I hung out of the car with the door open and revved and yeah, it's louder than I thought because it's so muffled by the firewall, glass, and engine/trans being between me and the pipes. Sigh, more things I'm unhappy about and writing on a list of "reasons why I'm selling my C8". I appreciate you pointing this out so I know there's a fundamental problem with mid-engine cars.

Sounds like an LS should! However, I can't/won't delete cats. Even if I can make codes disappear with a tune, there is a visual inspection in Maryland for registering the car, so if I ever sell it, I would need to swap them back out. Tuning is expensive and would void my remaining 2 years of powertrain warranty as well as most of what the GM extended protection plan would cover if I decide to purchase it.\

 

Spacing actuators out so they operate but dont close valve will set cel light. I tried that on my 2022.

 

I agree, the only way to keep the NPP valves open all the time is by using the plug in simulators. That is the only way to get maximum sound all the time. Track setting does not keep the NPP valves open all the time... not even close and even with the valves open the NPP system is still too quiet. I have the AWE touring cat back and use the plug in simulators for the AFM wire harness . The AWE touring has noticeably more sound than a NPP factory system in its loudest mode and has no AFM or NPP valves.

 

I guess I spend very little time cruising below 2000 rpm. If you're on the gas below 2000 rpm, the valves are open. If you're decelerating, the valves open. The only time I might be cruising below 2000 rpm is on a steady highway drive, in which case I'm fine with them closing down. But in normal driving, when you're accelerating and decelerating, the valves are open most of the time. Even at idle.