Npp exhaust with LTH, any sound change
#1
Le Mans Master
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Npp exhaust with LTH, any sound change
What kind of exhaust sound change will happen with LTH (with cats) while retaining the NPP ?? Louder, quieter, same?? or any change at all?? I really like the option the NPP offers
Thanks
NSF
Thanks
NSF
#2
Le Mans Master
My guess is it will be a little bit louder, and should be a little more throaty. When I put headers on my 05, thats what it did. Just enough to tell you had headers. I think you will like it.
#5
Le Mans Master
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50% really that's quite a lot more sound than I would want because with the NPP open its not exactly quiet now, but 50% more, I want more of a sound change than noise increase if that makes any sense
NSF
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#6
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I can only give you my experience with catted long tube headers and the NPP ....
During idle and during normal driving the sound will be about the same (just very slightly louder than with the stock exhaust manifolds), but when you put your foot in it and the NPP valves open up, it's much louder than before ... much!
Personally, I thought it was obnoxious when at full throttle, so I replaced the NPP mufflers with a Borla Touring axle-back system .... much better in my opinion while at full throttle and just very slightly louder at idle and during normal driving than the headers with the NPP.
2011 GS / A6
.
During idle and during normal driving the sound will be about the same (just very slightly louder than with the stock exhaust manifolds), but when you put your foot in it and the NPP valves open up, it's much louder than before ... much!
Personally, I thought it was obnoxious when at full throttle, so I replaced the NPP mufflers with a Borla Touring axle-back system .... much better in my opinion while at full throttle and just very slightly louder at idle and during normal driving than the headers with the NPP.
2011 GS / A6
.
Last edited by Turbo6TA; 02-14-2016 at 02:48 PM.
#7
Burning Brakes
https://www.corvetteforum.com/forums...d-sucks-2.html
Last edited by Curt D; 02-14-2016 at 04:09 PM.
#8
Racer
With the NPP closed I had a small/medium change in sound, not too noticeable unless you really knew your cars. You could hear the factory cam profile a little better. With an open NPP, HUGE difference. I had a factory x-pipe beforehand so I didn't expect too much of a change other than decibel level.
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#10
I am currently running Kooks LT Headers w/ an X-Pipe and hi-flow cats and the stock NPP exhaust. Pretty similar or most likely identical to what you would be running.
With the NPP flaps closed there is only a slight difference in sound, barely noticeable.
With the NPP flaps open the car is much louder with a much deeper throatier sound, it sounds awesome at IDLE and at WOT it sounds downright mean.
I personally love this setup because I still have the option to run very quietly, but when I'm in the mood for the muscle car sound it's one button push away.
With the NPP flaps closed there is only a slight difference in sound, barely noticeable.
With the NPP flaps open the car is much louder with a much deeper throatier sound, it sounds awesome at IDLE and at WOT it sounds downright mean.
I personally love this setup because I still have the option to run very quietly, but when I'm in the mood for the muscle car sound it's one button push away.
#11
Advanced
I am currently running Kooks LT Headers w/ an X-Pipe and hi-flow cats and the stock NPP exhaust. Pretty similar or most likely identical to what you would be running.
With the NPP flaps closed there is only a slight difference in sound, barely noticeable.
With the NPP flaps open the car is much louder with a much deeper throatier sound, it sounds awesome at IDLE and at WOT it sounds downright mean.
I personally love this setup because I still have the option to run very quietly, but when I'm in the mood for the muscle car sound it's one button push away.
With the NPP flaps closed there is only a slight difference in sound, barely noticeable.
With the NPP flaps open the car is much louder with a much deeper throatier sound, it sounds awesome at IDLE and at WOT it sounds downright mean.
I personally love this setup because I still have the option to run very quietly, but when I'm in the mood for the muscle car sound it's one button push away.
Great news. Mine will be going to the shop tomorrow for those exact mods....plus a cam. Can't wait.
#12
Drifting
I am currently running Kooks LT Headers w/ an X-Pipe and hi-flow cats and the stock NPP exhaust. Pretty similar or most likely identical to what you would be running.
With the NPP flaps closed there is only a slight difference in sound, barely noticeable.
With the NPP flaps open the car is much louder with a much deeper throatier sound, it sounds awesome at IDLE and at WOT it sounds downright mean.
I personally love this setup because I still have the option to run very quietly, but when I'm in the mood for the muscle car sound it's one button push away.
With the NPP flaps closed there is only a slight difference in sound, barely noticeable.
With the NPP flaps open the car is much louder with a much deeper throatier sound, it sounds awesome at IDLE and at WOT it sounds downright mean.
I personally love this setup because I still have the option to run very quietly, but when I'm in the mood for the muscle car sound it's one button push away.
Someone school me. I would love to learn from you folks
#13
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The stock exhaust manifolds are much shorter than a set of long tube headers, therefore, you need an aftermarket x-pipe (made for your brand of headers).
Your factory NPP muffler system will attach perfectly to the new x-pipe that comes with the headers you choose.
The other item to consider is whether or not you want cats. You can get your new x-pipe either with cats or without ... Personally, I would get the cats. In fact, you will only give up a couple of HP with them.
Your factory NPP muffler system will attach perfectly to the new x-pipe that comes with the headers you choose.
The other item to consider is whether or not you want cats. You can get your new x-pipe either with cats or without ... Personally, I would get the cats. In fact, you will only give up a couple of HP with them.
#15
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As you can see, the cats are welded into the x-pipe (not on the headers):
In the photo below, the x-pipe is attached to the ends of the headers with V-band style clamps. The cats are welded into the x-pipe just a few inches in back of those V-band clamps.
In the photo below, the x-pipe is attached to the ends of the headers with V-band style clamps. The cats are welded into the x-pipe just a few inches in back of those V-band clamps.
#16
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The system will be a little louder without cats. The exhaust will be a little more smelly without cats. You might gain 2 RWHP without cats.
And in California, you will be in [more] violation of the law driving a car without any cats at all.
And in California, you will be in [more] violation of the law driving a car without any cats at all.
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#18
Safety Car
Cats did not seem to hurt my torque or HP, this is the 1st and last (6th) of dyno pulls on a 95 degree day here in Florida.
#19
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St. Jude Donor '06-13,'16-'17, '19
This was using LG Motorsports long tube headers with their hi flow cats and without cats.
Tom
Last edited by TCW; 02-15-2016 at 04:57 PM.
#20
Le Mans Master
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Thanks for al the replies Question answered.
Additionally when I price out, say a "Kooks" 1'7/8" (or about any other system) with catted X pipe, all ceramic coated, that will bolt up to stock axle back system I come up at about $1900-$2000. Members have said they wont run that much or at least they didn't pay that price, HOW SO ?????
I cant quite justify that mark for what the return would be, plus I'm cheap. to me that's a lot of $$$$ for a set of "headers"
Thanks again
NSF
Additionally when I price out, say a "Kooks" 1'7/8" (or about any other system) with catted X pipe, all ceramic coated, that will bolt up to stock axle back system I come up at about $1900-$2000. Members have said they wont run that much or at least they didn't pay that price, HOW SO ?????
I cant quite justify that mark for what the return would be, plus I'm cheap. to me that's a lot of $$$$ for a set of "headers"
Thanks again
NSF