Pizz

I have a set of ARH mid length headers with high flow cats. I haven't installed them yet. I've already installed the Borla catless xpipe, Borla ATAK axle back exhaust and an AFE CAI. I really like the sound of this setup and that it goes back to stealth mode when the NPP valves close (great design Borla!).

I am curious what the headers will do to the sound, both with the NPP valves closed and open. Any insight would be great. Thanks

Can'tHave2MuchHP

It's going to get a lot louder. Even with the high flow cats. If you were going cat-less I'd put the "lot" in all caps and bold. The sound may get a bit raspier and higher pitched due to the pure sound of the engine coming into play. I'd expect the new Headers + Stealth Mode sound to be equally loud as your previous Stock Manifolds + Track Mode sound.

3 Z06ZR1

Not even close on the pure guess you made my friend! Headers are not a lot louder at all with the NPP. Just makes it sound much better.

AR 2 inch long tube headers with cats clean up the total exhaust sound but not much louder till you open to track mode then it is a little louder.

My 2015 has them and my 2017 sounds lame without so I'm adding headers to both cars

KnightDriveTV

Because you always talk to people in a demeaning tone like that, I assure you....you don't have friends on here.

Gxpz06

I agree with you and mine is only a guess since I only have a c7z on the way and will keep it bone stock ...

My guess is based on fact that c5z actually got quieter at idle with kooks as well as ls7 with npp both with catless mid pipes .., my friend did high flow cats on ls3 npp and it was actually louder then my ls7 catless .,

My belief is that restriction drouns especially at idle ..

I understood your tone 👍🏼

3 Z06ZR1

I was being nice actually since his information about headers and NPP was way off. Someone wanted a correct answer. Sorry if you
were offended. Well not really!
Actually that's very funny I was trying to help with some of the bad information about headers in general. I see you never see how CHTP talks to other he has been less than cordial to me in the past. So yeah I was being nice and could give a crap what you think. I assure you I have all the friends I need friends here and else where. Have to clean up from friends
coming over last night. About 10-12 or so will be coming over for my monthly UFC fight party tonight.

3 Z06ZR1

Mine is not a guess I have had headers on most of my Corvette's all with NPP as the catback. My 2017 has just turned 4k and I'm ordering headers and the 2300 blower this week. After driving my other Z06 equipt that way the headers are a must.

Streetrod782

While I don't have a Z my Z51 has the ARH mid length headers, borlaX pipe and the NPP exhaust. It's like this , the X pipe
Made it about 10-15% louder. The headers probably another 20% louder. At normal driving it's not that much louder. At WOT it screams like a pissed off cat. Hit it under an overpass and you'll likely make people pee a little bit. I pulled 42 and when she cold starts it shakes the house a bit. You'll love them!!

3 Z06ZR1

Yep can be loud be not for me so
I kept 42 and the other fuses in place and run normal closed exhaust.
The cold starts due sound a little angry Your set up might be a little louder with the borla x pipe over straight ARH longtubes with NPP. Plus I always get my headers coated. It may calm the sounds slightly.
Other than that cold start they are mostly not really much louder at all. Still way below illegal levels But the sounds you do hear are much sweeter.
UNTIL you run WFO then she screams very loud when you hit 4k and up!
Love the 2 inch headers though they really make the car feel a lot more sporty.

Can'tHave2MuchHP

Woah woah, let's get to straightening...

Alright first off, it's not a guess by any means, save for his Borla system which I'm not entirely familiar with, and if you read his post you'd see he didn't ask what it did with the STOCK NPP exhaust. The Borla ATAK axle-back is going to be SIGNIFICANTLY louder than the factory NPP in ALL situations and will be tuned differently.

I've owned and driven dozens of GM cars with headers. Done the before and afters. Done the builds. Headers louden them up, period. Especially at WOT, cold starts, and downshifts. My guess still holds true with his Borla ATAK exhaust. Ditching secondary cats (X pipe) doesn't compare to LT headers + high flows/no cats. Even the member who has the exact setup above said it got a quite a bit louder under WOT/Cold start etc. which again is what I said. Put it in quiet mode and it will likely be similar to what his current "open" or "track" mode is.
He's certainly quite miserable to deal with. But it's funny that he's that demeaning and confrontational and then he's WRONG on a lot of his information on top of that.
Again,

He wasn't talking about the GM NPP exhaust. He's running Borla ATAK. And what I said wasn't way off. And you contradict yourself, saying your second Z06 sounds "lame" without headers. So you're putting Headers on the second one. But then you say it's not much/any louder and my info is way off? You didn't even read his post correctly and realize he was talking about the Borla ATAK system and not the factory NPP. I'm able to admit that I'm not familiar with the Borla but give him some information on what will change, whereas you are just a contracting and confrontational mess. Don't you have anything better to do with your time?

Also, the ONLY times I have not been cordial to you is when you open your mouth and insert your foot like you commonly do. You think I'm the first one or the only one to notice? No. A vast majority of your posts seem to end up in controversy. Case and point, scroll up.

OP,

Your car will get quite a bit louder with Headers, especially on cold start and WOT. It won't be unmanageable though with the dual mode Borla system. Have fun.

3 Z06ZR1

You maybe right I just read the thread title and didn't read his post I know nothing about Borla X pipe or his cat back set only you cannot mix those with longtubes.
I would say they both get loud when they have open NPP but longtube headers do wail on open NPP and sound so much better.
The Op should have said shorty headers in the thread title not quite the same thing. Not stock NPP either it may get way louder. Most any car guy hears "headers" they think long tubes not shorty's.
The stock exhaust does sound very lame and runs lame too. All most all my Corvette's get headers they make the exhaust sound better not much louder

at all 95 percent of time no one knows you have headers
The thread title reads "What do headers do to NPP Exhaust sound?

So that question on exhaust sound. That I know exactly what it does.
I was commenting on AR longtubes with the stock NPP. Which I had on my 2008 C6, 2008Z06, and 2015 Z06 and am adding to my 2017 Z06. Which is a pretty mild set up has a good sound and is nice to able to still go quiet. But still makes good power.

upcharger

Pizz

Thanks for the "spirited" feedback, guys. I appreciate the first hand knowledge.

zergi06

Pizz

I can't speak for anyone else, but in my case, I wanted a deaper tone while getting more HP/Torque. The CAI, catless mid-pipe, and axle back exhaust gets about 30 hp without a tune. When I tune it, who knows? Adding the manifold will add more hp, but I want it to not sound like a drag car when I tour with it. That's the purpose of my original post.

zergi06

DomLS3

I put 2" longtubes with no cats on my car going into the stock NPP. It was not that much louder at all. When the valves are closed it's so quiet... like almost can't even hear it when I'm driving quiet. With the valves open it's pretty loud on a cold start but once it warms up it's not loud at all, nor is it that loud cruising. It's only real loud at WOT.

3 Z06ZR1

Sounds like the headers and NPP is for you. The headers clean up the sound when in track mode and it is not much louder in tour than tock but a much clean tuned sound comes with the tuned header pipes w/ cats.

Halltech gets you 40-50 rear wheel and when tuned and headers it is more like 75 -80 rear wheel. I have the Halltech and headers and dyno'd each step. Add the 2300 and it goes up to close to 150 more. About 775hp or so on pump gas.

DomLS3

775 rwhp with a 2300, headers and cai only? No meth or E85? I don't think so.

Tort

Guessing he means crank hp and not whp?