[Navigator]

I recently bought a 2020 Camaro 2SS with a manual transmission and the NPP exhaust and the exhaust volume seems a lot quieter than expected.

I used to own a 2017 Camaro SS manual with NPP and that always sounded pretty aggressive and loud as far as I recall. I then bought a Shelby GT350 with the resonator delete (which basically gives it the same exhaust setup as the GT350R). While that was definitely louder than the Camaro and one of the best exhaust notes I’ve ever heard, I don’t remember it being that much louder than the Camaro around the time I bought it.

Now that I’m back in a Camaro with NPP, the exhaust seems way quieter than I recall. I’ve flipped through the modes, confirmed the valves viewable through the tailpipes are opening and closing, and can hear a slight difference in volume between the open and close modes. I’ve pulled the fuse and it still sounds pretty quiet unless I’m really getting on it aggressively. Even with no fuse it seems about as loud as I recall stealth mode being last time I owned a Camaro. It honestly sounds about the same as being in a Chevy V8 Silverado or Tahoe with a stock exhaust, which is a pretty muffled sound.

Is there something else that could be causing this to sound too quiet, like a cat issue? Are there other valves other than the visible ones that could be stuck? Did something change in volume between 2017 and 2020? I know they revised the exhaust between then, but I thought that was more to add crackles and pops than to change volume.

[bishopts]

Maybe remove the cats? I'm running NPP with no actuators. And long tubes with cat delete, It's loud when I'm on it but at idle or cruising on the highway its pretty much as loud as all the cars around me. Also there is a huge difference in sound when the windows are up vs down.

[Navigator]

I was thinking about a secondary cat delete but wondering if something else might be going on before I do that. I seem to remember my 2017 SS being a lot louder at startup and low RPMs.

[bishopts]

Secondary cat delete doesn't require you tuning out codes so really nothing to lose with that one.

[bishopts]

Post a cold start video tomorrow.

[speedyink1]

I certainly wouldn't call my 2023 with NPP quiet.. Especially not pickup truck quiet. It's only loud on cold starts and when I get on it though. If I cold start with the window down/door open it's almost hurt my ears loud when parked in the garage. Putting around it's pretty quiet, but when I get on it she's definitely louder then a pickup truck. It's got a bit of a rumble at low RPMs, but definitely not as loud as an old V8 muscle car.

[Navigator]

Originally Posted by speedyink1

If I cold start with the window down/door open it's almost hurt my ears loud when parked in the garage.

My GT350 was definitely that kind of loud, but this seems at least 50% quieter. Even cold starts in legit cold temperatures (sub freezing) just sound about the same as firing up my dad’s 2015 Silverado with a stock exhaust, nothing special sounding at all.

[JT6Speed]

I don't think anything physically changed from 2016 on up. If the fuse is pulled there shouldn't be anything holding it back.

Must be a perception thing, I know my car feels quiet compared to other Corvette's/Mustang's/etc. that have screaming loud exhausts.

[GroundhogSS]

The fuse pull should definitely help. I recall several years ago some people having the flaps on the NPP sticking. Check with a flashlight to be sure they are fully open

[Navigator]

Originally Posted by GroundhogSS

The fuse pull should definitely help. I recall several years ago some people having the flaps on the NPP sticking. Check with a flashlight to be sure they are fully open

The valves I can see through the tailpipes are fully open. Is there another set of valves beyond that hidden from view? Or is it just the automatic transmissions (which I don’t have) that have the extra AFM valves?

[JT6Speed]

Originally Posted by Navigator

The valves I can see through the tailpipes are fully open. Is there another set of valves beyond that hidden from view? Or is it just the automatic transmissions (which I don’t have) that have the extra AFM valves?

No extra valves on a manual. We don't need AFM valves because we are always running on 8!

I saw a video back where Phastek was testing some Stainless Works exhaust combos. At 4K rpm in track mode, the stock exhaust put out 101 decibels. Not bad for stock at all.

You can always put the back seats down for more cabin noise

[RIPws6]

Probably AFM kicking in and putting the car in V4 mode. I had MBRPs put on and it sounded great until AFM silenced it after a few gears.
Get the Range device and keep it in V8 all the time.

[speedyink1]

Originally Posted by Navigator

My GT350 was definitely that kind of loud, but this seems at least 50% quieter. Even cold starts in legit cold temperatures (sub freezing) just sound about the same as firing up my dad’s 2015 Silverado with a stock exhaust, nothing special sounding at all.

Weird.. I know others on here use stealth mode for cold starts to not piss off their neighbors. My neighbors have mentioned mine to me, one of them from down the road a few houses.


...They weren't complaints by the way (otherwise I'd switch to stealth mode starts). The one from down the road has a 4 Cyl Turbo 6th gen Camaro and she says my startup sound makes her want to sell it to get a V8 one (whoops!)

[ember1205]

Originally Posted by RIPws6

Probably AFM kicking in and putting the car in V4 mode. I had MBRPs put on and it sounded great until AFM silenced it after a few gears.
Get the Range device and keep it in V8 all the time.

It's a manual... While the AFM hardware is in the motor, there is no programming to engage it. Car is always in V8 mode no matter what...