NPP vs?
Melting Slicks
Joined: Dec 2006
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From: Exhaust Commander Wireless Bi-Mode Exhaust Controllers, Innovative and advanced technology! --- Check out our website @ www.sunsetorangecreations.com
St. Jude Donor '13
One more point, the NPP if set to quiet will open up if you go WOT. The WOT will take the vacuum down to 0 and the vacuum is what holds the flaps closed. So you get loud if you hit the throttle hard. There is a way to remain quiet during WOT but you need to hook in a vacuum reservoir to hold the flaps closed during WOT. I don't have that. If I go WOT or into boost, the flaps open up and it gets noisy back there.
Also note, I have LT headers and no cats. It would be very loud and have drone with most aftermarket systems. The NPP makes it "stock" quiet when the flaps are closed.
Elmer
Also note, I have LT headers and no cats. It would be very loud and have drone with most aftermarket systems. The NPP makes it "stock" quiet when the flaps are closed.
Elmer
If yours is opening up right when you go to wot then the check valve is not working properly. The check valve has a diaphragm inside. You check valve may be damaged or missing.
Moderator emeritus
Joined: Jun 2001
Posts: 18,599
Likes: 3,951
From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
The NPP exhaust whether retrofitted or from the factory should not open just because of WOT. There is a vacuum check valve that stores vacuum in the system even when the car is at wot and the intake manifold is at zero vacuum.
If yours is opening up right when you go to wot then the check valve is not working properly. The check valve has a diaphragm inside. You check valve may be damaged or missing.
If yours is opening up right when you go to wot then the check valve is not working properly. The check valve has a diaphragm inside. You check valve may be damaged or missing.
I think missing would be the answer. I saw no check valve on there as I was doing the install.
Elmer
Safety Car
Joined: Mar 2009
Posts: 4,101
Likes: 719
From: Northeast MA & Mad Beach FL
Under normal acceleration the flaps open at 3,500 RPM.
Usually 30 -50% throttle as the RPM's climb.
But when the throttle is at 80% - 100%, then the flaps will open at 2,800 RPM.
Considering how fast the RPM's climb when going directly to WOT combined with the flaps now opening at 2,800 with 80-100% throttle, there's probably only a second or two before the flaps open.
In other words, the exhaust is most likely working correctly, but it's happening so fast, for all intent and purposes, they're opening right away
That's been my experience
Drifting
Joined: Sep 2006
Posts: 1,657
Likes: 5
From: Orange CA
I prefer Corsa or Borla. My friends that have NPP usually leave it open or pull the fuse. NPP 2 pipes get dirtier than the other 2 and have been known to drone, that bothers me. With the Corsa system I can control the sound with the throttle. And it is a better quality part and you don't have the unsightly vacuum valves showing my 2¢
Moderator emeritus
Joined: Jun 2001
Posts: 18,599
Likes: 3,951
From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
There is also a chance your exhaust is working fine.
Under normal acceleration the flaps open at 3,500 RPM.
Usually 30 -50% throttle as the RPM's climb.
But when the throttle is at 80% - 100%, then the flaps will open at 2,800 RPM.
Considering how fast the RPM's climb when going directly to WOT combined with the flaps now opening at 2,800 with 80-100% throttle, there's probably only a second or two before the flaps open.
In other words, the exhaust is most likely working correctly, but it's happening so fast, for all intent and purposes, they're opening right away
That's been my experience
Under normal acceleration the flaps open at 3,500 RPM.
Usually 30 -50% throttle as the RPM's climb.
But when the throttle is at 80% - 100%, then the flaps will open at 2,800 RPM.
Considering how fast the RPM's climb when going directly to WOT combined with the flaps now opening at 2,800 with 80-100% throttle, there's probably only a second or two before the flaps open.
In other words, the exhaust is most likely working correctly, but it's happening so fast, for all intent and purposes, they're opening right away
That's been my experience
That and I said "boost" too. I do not have a stock install. My NPP is connected into the side of my E-Force. There isn't ANY RPM control on my car for the flaps. The only force holding my flaps open is vacuum. No vacuum, flaps are open. I think my exhaust is working just fine!
Elmer
Life Time NCM #2196
Joined: Sep 2004
Posts: 82,586
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From: Converse TX
The only other alternative to NPP (for a bi-mode exhaust) seems to be the B & B Fusions. And they are actually more expensive.
The reason we put NPP exhaust on the car is solely for the ability to adjust the sound. Otherwise, we would just find a muffler with the sound we like (Corsa, Borla, Magnaflow, etc.) and put it on.
In my opinion, installing the NPP or the Fusions and leaving it on one setting kind of defeats the purpose of the adjustability or the bi-mode feature.
I have my NPP - I bought it used here on CF - and it's controlled with a kit from Sunset Orange Creations, which is synched to the sun visor controls.
The reason we put NPP exhaust on the car is solely for the ability to adjust the sound. Otherwise, we would just find a muffler with the sound we like (Corsa, Borla, Magnaflow, etc.) and put it on.
In my opinion, installing the NPP or the Fusions and leaving it on one setting kind of defeats the purpose of the adjustability or the bi-mode feature.
I have my NPP - I bought it used here on CF - and it's controlled with a kit from Sunset Orange Creations, which is synched to the sun visor controls.
I went with a ZR1 complete exhaust as I wanted it to be quiet when I wanted and louder when I wanted and I have no drone when closed and not bad when open, like when I had Stainless Works on my C5. If I wanted an aftermarket I would of went with Corsa Sports for the no drone, like when I did have Pace Cars on my C5 and I ran it with no cats and 1 7/8 Headers it was loud when you were on the gas and quiet on a cruise
Safety Car
Joined: Jan 2009
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From: Mooresville (Race City USA) NC
Many like to close, or mostly close, the system when driving in neighborhoods at night, when taking their wife out, when taking a long trip, when driving past hospitals, churches and schools in session, when in a funeral procession, etc., in order not to be obnoxious disturbers of the peace.
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Safety Car
Joined: Mar 2009
Posts: 4,101
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From: Northeast MA & Mad Beach FL
That and I said "boost" too. I do not have a stock install. My NPP is connected into the side of my E-Force. There isn't ANY RPM control on my car for the flaps. The only force holding my flaps open is vacuum. No vacuum, flaps are open. I think my exhaust is working just fine!
Elmer
Elmer
Le Mans Master
Joined: Aug 2005
Posts: 5,335
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From: Eagle River AK
St. Jude Donor '06-'07-'08-'09-'10,'14
Granted, what sounds 'good' is in the ear of the beholder. For me, sound is an integral part of the performance car experience and sadly stock Corvettes sound weak. I realize there are government constraints and Corvette tries to appeal to a certain demographic but even a Mustang sounds better. While I commend GM for trying to address the poor sound quality of the Corvette I've never been a fan of the NPP exhaust. It's mechanically 'gimmicky' and frankly doesn't sound as good as certain aftermarket exhausts. I want a high performance car to sound like one 24/7....not a part-time exhaust the only sounds (somewhat) better in a certain RPM range. With the NPP exhaust many opt for the aftermarket 'switched' exhaust feature and many others simply leave the valves open all the time. This IMO evidences the NPP is lacking straight from the factory. Conceptually, I think flipping a switch to change the volume of your car is hokey. If I want my car to be louder I'll press my right foot down. 
I think you're much better off going with a quality aftermarket exhaust such as made my Corsa or Borla. Some aftermarket exhausts try to mimic the muscle car sound but often come-off being loud and obnoxious. I want a drone-free exhaust that generates a strong, clean exhaust note reflective of what's under the hood. Keep in-mind if you make future engine modifications it will effect the sound of an exhaust greatly. If you're undecided arrange to visit a local Corvette club gathering or a nearby road course venue and listen to various Corvette exhausts firsthand. Good luck whatever you decide on.
I think you're much better off going with a quality aftermarket exhaust such as made my Corsa or Borla. Some aftermarket exhausts try to mimic the muscle car sound but often come-off being loud and obnoxious. I want a drone-free exhaust that generates a strong, clean exhaust note reflective of what's under the hood. Keep in-mind if you make future engine modifications it will effect the sound of an exhaust greatly. If you're undecided arrange to visit a local Corvette club gathering or a nearby road course venue and listen to various Corvette exhausts firsthand. Good luck whatever you decide on.
Couldn't have said it better.
Former Vendor
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$899.00 shipped lower 48 states.
http://www.ghlexhaust.com/C6-Corvett...008-822222.htm
Pro
Joined: Dec 2009
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From: Scarsdale New York
I believe the NPP exhaust option is about $1,200. I didn't get it on my 09 so I decided to get an aftermarket exhaust. A high quality exhaust though is not less then $1,000 new. I got my Corsa Sport brand new for $1,250, which is a great price, and think the sound is better then NPP. It def sounds better at lower RPMS and screams at WOT. Plus, the popping and gurgle and decel and downshift is worth every penny.
Thread Starter
Race Director
Joined: Nov 2004
Posts: 11,065
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From: Central Ma
I believe the NPP exhaust option is about $1,200. I didn't get it on my 09 so I decided to get an aftermarket exhaust. A high quality exhaust though is not less then $1,000 new. I got my Corsa Sport brand new for $1,250, which is a great price, and think the sound is better then NPP. It def sounds better at lower RPMS and screams at WOT. Plus, the popping and gurgle and decel and downshift is worth every penny.
See post directly above yours.
Melting Slicks
Joined: Oct 2003
Posts: 2,655
Likes: 5
From: Brea CA
ah...
Many like to close, or mostly close, the system when driving in neighborhoods at night, when taking their wife out, when taking a long trip, when driving past hospitals, churches and schools in session, when in a funeral procession, etc., in order not to be obnoxious disturbers of the peace.
Safety Car
Joined: Oct 2003
Posts: 4,024
Likes: 13
From: Loveland CO to Central Coast CA
...it's louder than I like fully opened. But too quiet fully closed.
...I installed collars that keep it slightly open all the time. Very pleased!
The collars are easily adjustable... I set it ~1/4". The sound is perfect for me. And it feels the same as stock.
With the engine off...
Slightly open at idle...
Pro
Joined: Dec 2009
Posts: 729
Likes: 23
From: Scarsdale New York
Yes I know you can purchase brand new exhaust systems for less the $1k, such as GHL or Flowmaster. But I am reffering to a high quality exhaust such as Corsa, or Borla. Corsa is more expensive because it gives you a high quality performance car sound that'll scream at WOT, but won't drone or resonate at cruise. They also look great and are made from high quality materials. The new Borla systems also give an awesome note.
The cheaper exhausts can still sound great on the outside, but will kill your ears on the inside and can have cheap looking tips. That's why they are less expensive.
The cheaper exhausts can still sound great on the outside, but will kill your ears on the inside and can have cheap looking tips. That's why they are less expensive.
Team Owner
Joined: Oct 2007
Posts: 26,745
Likes: 694
From: PA
Toning your exhaust is like saying you bought a red car but going past a cop you want it to change to silver because silver cars dont get as much attention.
May as well have your Vette shape-shift in to a prius when you are near hippies so you dont offend them too. lol
I prefer Corsa or Borla. My friends that have NPP usually leave it open or pull the fuse. NPP 2 pipes get dirtier than the other 2 and have been known to drone, that bothers me. With the Corsa system I can control the sound with the throttle. And it is a better quality part and you don't have the unsightly vacuum valves showing my 2¢
Yes I know you can purchase brand new exhaust systems for less the $1k, such as GHL or Flowmaster. But I am reffering to a high quality exhaust such as Corsa, or Borla. Corsa is more expensive because it gives you a high quality performance car sound that'll scream at WOT, but won't drone or resonate at cruise. They also look great and are made from high quality materials. The new Borla systems also give an awesome note.
The cheaper exhausts can still sound great on the outside, but will kill your ears on the inside and can have cheap looking tips. That's why they are less expensive.
The cheaper exhausts can still sound great on the outside, but will kill your ears on the inside and can have cheap looking tips. That's why they are less expensive.
Burning Brakes
Joined: Nov 2011
Posts: 1,042
Likes: 283
From: West Dundee IL
2024 C5 of the Year Finalist - Modified
St. Jude Donor '12-'13
I found it cheaper to buy Z06 mufflers and have them modified to fit the base 2.5" system. The tips are a little bigger and look much better too IMO.
Burning Brakes
Joined: Mar 2007
Posts: 936
Likes: 286
From: Shreveport Louisiana
Granted, what sounds 'good' is in the ear of the beholder. For me, sound is an integral part of the performance car experience and sadly stock Corvettes sound weak. I realize there are government constraints and Corvette tries to appeal to a certain demographic but even a Mustang sounds better. While I commend GM for trying to address the poor sound quality of the Corvette I've never been a fan of the NPP exhaust. It's mechanically 'gimmicky' and frankly doesn't sound as good as certain aftermarket exhausts. I want a high performance car to sound like one 24/7....not a part-time exhaust the only sounds (somewhat) better in a certain RPM range. With the NPP exhaust many opt for the aftermarket 'switched' exhaust feature and many others simply leave the valves open all the time. This IMO evidences the NPP is lacking straight from the factory. Conceptually, I think flipping a switch to change the volume of your car is hokey. If I want my car to be louder I'll press my right foot down.
I think you're much better off going with a quality aftermarket exhaust such as made my Corsa or Borla. Some aftermarket exhausts try to mimic the muscle car sound but often come-off being loud and obnoxious. I want a drone-free exhaust that generates a strong, clean exhaust note reflective of what's under the hood. Keep in-mind if you make future engine modifications it will effect the sound of an exhaust greatly. If you're undecided arrange to visit a local Corvette club gathering or a nearby road course venue and listen to various Corvette exhausts firsthand. Good luck whatever you decide on.
I think you're much better off going with a quality aftermarket exhaust such as made my Corsa or Borla. Some aftermarket exhausts try to mimic the muscle car sound but often come-off being loud and obnoxious. I want a drone-free exhaust that generates a strong, clean exhaust note reflective of what's under the hood. Keep in-mind if you make future engine modifications it will effect the sound of an exhaust greatly. If you're undecided arrange to visit a local Corvette club gathering or a nearby road course venue and listen to various Corvette exhausts firsthand. Good luck whatever you decide on.
Had corsa sports on my c5 and got nothing but compliments. I'm debating corsa extremes or borla ataks for my c6. Choices choices.....
Last edited by bgspot; Aug 15, 2012 at 10:07 AM.
Burning Brakes
Joined: Mar 2007
Posts: 936
Likes: 286
From: Shreveport Louisiana
Many like to close, or mostly close, the system when driving in neighborhoods at night, when taking their wife out, when taking a long trip, when driving past hospitals, churches and schools in session, when in a funeral procession, etc., in order not to be obnoxious disturbers of the peace.