Help! Its not an NPP exhaust so what is it?

Bonnell · 07-30-08, 06:43 PM

When I purchased my 2008 coupe last week it did not have the NPP exhaust on it. I asked to add it. They said no problem that they would order it.

Several people have made comments that adding NPP is not possible so this morning when I took it in I asked again and explained the issue. The service manager said that they had added many and it was no problem.

I want you to understand that the dealership has been very accomodating and very helpful.

I went to get the car just after lunch and I had a meeting that I had to run back to so when I noticed that I did not see any butterfly valves I asked about it and he did not one one way or the other if they should be there like on the Z06. I had to run back to work.

This afternoon on the way home it was apparent that nothing dramatic happens when I hit 3500 rpm. There seems to be what I assume some of you call drone at highway speeds.

The jury is still out. The original exhaust had a deep growl that I really liked. I am noth sure this sounds as good except at idle. It sounds way better at idle than the tame original.

I called when I got home and he was very patient as I explained the difference between the Z06 exhaust and the non-Z06 NPP exhaust. He could not find any other part numbers for the 2008 Corvette except the original and the GM performance exhaust that they put on today.

He is going to see what else he can find out but right now all I know is that I had a $1,625 exhaust installed and all I know is that it has bigger tips, is louder at idle and the GM part# is 19172324.

I have posted some pics below. If you can identify this exhaust and tell me anything about it I would apreciated it. It seems you guys know more about my car than the dealership does.

The imprint on the tip is the C6 Corvette flag with CCA underneath:

Gorgon · 07-30-08, 09:47 PM

My understanding is that the GM Performance Exhaust is not the NPP exhaust, but it a GM badged aftermarket exhaust made by Corsa or maybe B&B. Hopefully others with some more knowledge will pop in soon.

Leon

Bonnell · 07-31-08, 08:33 AM

Yep, it is aftermarket and it drones. I am having the original put back on tomorrow. They sounded good to begin with. I just wanted the NPP.

Tuna · 07-31-08, 09:05 AM

It is not the NPP exhaust. NPP is not something a dealer can install on a non-NPP car without a lot of extra work.

I'm sure the dealer was trying to help and he knew that GM has a 'dealer installed' optional exhaust system. He just didn't know that the 'optional' exhaust was not NPP or dual mode like the Z06. So he thought he was doing the right thing.

twiget · 07-31-08, 10:29 AM

There was a thread about adding NPP to a non-NPP car a while back. You can find the thread here. I think the consensus is that it is possible to have the factory system installed, but not worth the effort.

You might be interested in this though; there is an aftermarket "NPP in a box" system. Just have the GM NPP mufflers installed on your car and install the system. It is supposed to work the same as the stock NPP system.

Jason

**Hib Halverson** · 07-31-08, 11:26 AM

The exhaust in the pics is not the OE, bi-state, exhaust which is the NPP option and is stock on Z06 and ZR1.

Also, my understanding, based in an interview with CORSA people in mid-07, is that the aftermarket, C6 exhaust sold by GM's Performance Parts program is no longer made by CORSA. Initially, CORSA did make the system, but later, in the interest of cutting cost, GMPP sourced the exhaust from another manufacturer. I should add that it's highly unlikely that it's a B&B because 1) most of the time B&B products are way loud...louder than GM would want and 2) B&B, being a high-quality product, would cost too much.

While it is possible to add NPP to an 08 or 09 built without it, the complexity and cost of the job would exceed the benefits and, if it's more noise you want, you can get that (without drone) by buying one of the aftermarket systems from Flowmaster or CORSA, both of which make exhausts that are louder than stock (but not really loud) and have a much lower level of "drone" than the GMPP system or some of the other aftermarket systems.

That said, if you bought an 08 not originally equipped with the RPO NPP and a dealer told you that, as part of the deal, it would retrofit the NPP system to the car and you have that in writing; I'd go back to the dealer and demand it fufills its promise or take the car back and give you a refund.

**Hib Halverson** · 07-31-08, 11:37 AM

PS:
I just checked with CORSA's PR firm and it does not manufacture the GMPP exhaust for C6es and has not made them for a couple of years.

Bonnell · 07-31-08, 02:39 PM

Tuna is correct. It is not the NPP but the service people thought it was. I finally talked with the service manager and he explained that they simply would not know how to do an NPP install.

They will put my old exhaust back on for me or work something else out. They are being very fair and above board.

I am set to have the old exhaust put on tomorrow. Meantime I am trying to decide once and for all if that is what I want or if the GCA is desireable. The drone really seemed loud at first but I have gotten used to it. In fact this exhaust does sound better than the originals in some RPM ranges and at idle.

Thanks for all of the input.

**Now since I have such knowledgeable people on this thread, I am scheduled to have the 3M clear bra product on my car next weekend. It will be the nose and about 18 inches up the hood, behind each wheel, the entire rocker panel and the kick plate where shoes most commonly rub and both mirrors. Haulter Body is certified and surpasses the 3 year 3M warranty with lifetime warranty against yellowing or any other defect. $900 including tax. Any comments?

Bonnell · 07-31-08, 02:42 PM

Anyone need a mild-2-wild kit cheap?

mmorse · 07-31-08, 02:51 PM

My advice would be to leave the performance exhaust on. My '08 came with the NPP and, IMO, is not worth the money. I found it to be way too mild. I pulled the fuse so the flap is open all the time. Still not all that great sounding and it drones pretty good at certain speeds. If I knew then what I know now, I would not have gotten the NPP. Then again, I like nice growl.

Bonnell · 07-31-08, 03:28 PM

Quote:

Originally Posted by mmorse

My advice would be to leave the performance exhaust on. My '08 came with the NPP and, IMO, is not worth the money. I found it to be way too mild. I pulled the fuse so the flap is open all the time. Still not all that great sounding and it drones pretty good at certain speeds. If I knew then what I know now, I would not have gotten the NPP. Then again, I like nice growl.

Thanks MMorse. It is good to have feedback on the NPP. I am leaning that way now. The original exhaust had a nice growl to it and no drone but these sound really good at idle and low speed so I may just keep them for a while.

Tuna · 07-31-08, 04:16 PM

I have NPP on my '08 vert and I'm very happy with it. I also have the Mild-2-Wild addition with it always in the 'wild' mode at start. With the top down, it's always wild.

However, with the top up and the windows up, 'wild' drones inside and is annoying. That's when I press the button on the fob and put it in the 'mild' mode. I'm not sure how a coupe responses with the NPP open all the time.

Bonnell · 07-31-08, 09:20 PM

Quote:

Originally Posted by Tuna

I have NPP on my '08 vert and I'm very happy with it. I also have the Mild-2-Wild addition with it always in the 'wild' mode at start. With the top down, it's always wild.

However, with the top up and the windows up, 'wild' drones inside and is annoying. That's when I press the button on the fob and put it in the 'mild' mode. I'm not sure how a coupe responses with the NPP open all the time.

Being able to turn it off when you want to is really nice.

twiget · 07-31-08, 09:49 PM

Quote:

Originally Posted by Tuna

I'm not sure how a coupe responses with the NPP open all the time.

There is a definite drone at around 1500rpm, which coincidentally is 70mph in 6th gear. When I'm cruising around town, I usually have the NPP off, so the pipes are open. When I'm headed down the interstate, I flip the switch so I don't have to listen to the droning.

Jason

**Hib Halverson** · 07-31-08, 10:16 PM

I have a "clear bra" on my 95 which was installed six years ago. It is still in place, doesn't appear to have changed much. Very durable and prevents stone chips.

It's a great product.