NPP with Headers

[Anaconda]

Yeah right now the decibel reading in my car on the highway is anywhere from 80-93 decibels. Gets a little annoying after a while. Wonder of the X-pipe will make much of a difference? I have the stock resonators and the NPP mufflers welded on, flaps open.

[old motorhead]

Originally Posted by Fraxum

Not on my car. With LTs, cats and the standard NPP mode just the idle and wide open are loud. The idle is about like a slightly loud catback. Wide open is like a loud catback but not as obnoxious as LTs and muffler delete.

When cruising in this mode it sounds good and there is no drone. With the flaps open all the time it is like a slightly loud catback, except at full throttle. And surprisingly there is no drone with the flaps wide open unless you are going up a slight hill.

After going to the track and driving around a bit, the standard NPP mode setup is very livable with LTs. And anyone who has neighbors who complain about the start-up are whiners. It's not that bad. But the loud wide open sound under load Is not at all sweet. There is a tinny clipping to the sound that ruins it for me. This sound is common to LS3s with the stock cat-back and LTs. My '11 SS was one of those for a while. And if there any police around you will surely get their attention with your volume. Dual mode exhaust is definitely a neat concept.

I have the Exhaust Commander, so my only choice is standard NPP mode or open all the time. This is hooked up to my garage door opener which is cool. But for now I will not be leaving the flaps open all the time except at the track. It would be preferred to have a third mode where you can leave the flaps closed all the time.

I can live with this NPP+LTs+cats+Exhaust Commander setup just by selecting the stock NPP mode action and staying out of full throttle. But this sounds like less fun. Every once in a while on a deserted stretch of road....

So I may go with this x-pipe leftover from my '11 SS in the near future:

Any body want a working Sony TV with a washed out picture?

This is the same part recommend by Tyler and it works just like he says. Before I installed it I looked inside it and I don't think it would increase or decrease restriction, but it does quiet and mellow down the tone. And leaving the stock LS3 resonators in place probably helps too.

Perfect. THat was what I was wanting to hear. I had the NPP system with Mild to Wild switch on my vette and loved it. The damn things developed internal cracks and began a rattle/vibration thing that was too annoying to ignore. The fix was to cut the cans open and weld up the cracks in the bulkheads. I had no confidence in the fix being permanent though. I jerked them out and replaced with Corsa's. I do miss the ability to go from stock like quiet to stupid loud at the push of a button. The Corsa's are a little louder than the closed NPP's at cruise. About the same at WOT as the NPP's open. Hope the Camaro NPP system is less problematic than the vette's. Cracking internal bulkheads is quite common on the vette system. The vette system has been out since '08. Hopefully GM has learned from their mistakes and the Camaro version is more reliable.

[Fraxum]

Originally Posted by Anaconda

Yeah right now the decibel reading in my car on the highway is anywhere from 80-93 decibels. Gets a little annoying after a while. Wonder of the X-pipe will make much of a difference? I have the stock resonators and the NPP mufflers welded on, flaps open.

It worked on my '11 SS. I started out with the LTs, high flow cats, and the stock cans. But that tinny crackling wide open sound was not to my liking. So I went with a Magnaflow "Street" axle back. This was not too loud and cured the crackle, but there was too much drone. So then I went with the MF xpipe. No more drone and it was quite a bit quieter. But the sound was very sweet and wide open it had a powerful ripping sound.

So I think with the NPP Flap the same effect can be achieved with the added advantage of the Flaps letting it all hang out when you want. I will probably get these put on next week. The xpipe is cheap, it cost more to have it installed if I remember than I paid for the xpipe.

Originally Posted by old motorhead

Hope the Camaro NPP system is less problematic than the vette's. Cracking internal bulkheads is quite common on the vette system. The vette system has been out since '08. Hopefully GM has learned from their mistakes and the Camaro version is more reliable.

I didn't know about this. Wouldn't the warranty cover the problem?

[t&t moyer]

Originally Posted by Fraxum

It worked on my '11 SS. I started out with the LTs, high flow cats, and the stock cans. But that tinny crackling wide open sound was not to my liking. So I went with a Magnaflow "Street" axle back. This was not too loud and cured the crackle, but there was too much drone. So then I went with the MF xpipe. No more drone and it was quite a bit quieter. But the sound was very sweet and wide open it had a powerful ripping sound.

So I think with the NPP Flap the same effect can be achieved with the added advantage of the Flaps letting it all hang out when you want. I will probably get these put on next week. The xpipe is cheap, it cost more to have it installed if I remember than I paid for the xpipe.



I didn't know about this. Wouldn't the warranty cover the problem?

This really has me thinking now. The combination of parts plays such a big part in sound, tone, noise, ect. As mine sets with the headers, cat-less mids and stock NPP with the fuse pulled it's a crackling SOB. I'd like to keep the NPP but might have to look into the MF x-pipe to settle things down a little.

Sounds like an over the winter project when she gets fitted with LTs, cam and a retune.

[Msmall143]

Who is and who is not tuning as they add the headers. Seems few if any are mentioning it

[ST1LE]

Very few add LT's and don't tune. I think the vast majority get tuned along with header install, and therefore it isn't mentioned as its a given in most builds.

[JDP Sales]

Originally Posted by Msmall143

Is this x pipe plug and play?

It will have to be welded in, So I do suggest professional installation unless you have a welder and the skills to get it done.

Originally Posted by Msmall143

Who is and who is not tuning as they add the headers. Seems few if any are mentioning it

Most tune immediately. Most of those who don't are just waiting to get a few more mods in place before tuning or saving up for the tune. The car will physically run fine without the tune, but you will get a check engine light for a cat code.

Best regards,

Tyler
888-308-6007

[VOGGS-LS3-1LE]

Will long tube headers void the power train warranty?

[ST1LE]

Originally Posted by VOGGS-LS3-1LE

Will long tube headers void the power train warranty?

No, but the tune will.That is the most likely scenario, but does depend on where you go though.

[willc1980]

get a tuner and just reflash to the stock tune before you take it in for service?

[t&t moyer]

Originally Posted by willc1980

get a tuner and just reflash to the stock tune before you take it in for service?

Nope, when the dealer plugs in they will see that it's been flashed already. The computer has a counter.....

[willc1980]

Originally Posted by t&t moyer

Nope, when the dealer plugs in they will see that it's been flashed already. The computer has a counter.....

how many times....but can they see what was done? if not they cant prove it was modified, just that it was flashed, could have been reflashed with a stock program for all they know

and something has to happen for them to void a warranty and they have to reasonably prove it was caused by what you did

[dixonk]

Originally Posted by willc1980

how many times....but can they see what was done? if not they cant prove it was modified, just that it was flashed, could have been reflashed with a stock program for all they know

and something has to happen for them to void a warranty and they have to reasonably prove it was caused by what you did

I found out last week that on the 12 and up they pull ECM history. It shows the tune and parameters. Had the car in at Abel for warranty work and they advised against tuning if you cherish the power train warranty.

Sent from my SCH-I545 using Tapatalk 4

[old motorhead]

They CAN deny warranty for just about any reason under the sun. That throws the ball back in your court. Are you going file a lawsuit against GM to force them to honor the warranty? Good luck with that one