I have a base 2007 M6 stock exhaust. I'd like to have the capability of switching from quiet to loud. So, my two options are 2008 NPP or full manifold to mufflers Z06 exhaust. What sounds better? I'm sure performance goes to Z06. NPP should be cheaper. I don't want to go aftermarket bi mode. Thoughts? Thanks.

 

NPP is louder by a little, most prefer it to the Z06.

Z06 mufflers are usually cheaper than NPP by about half (for used anyway).

You wouldn't need full manifold to muffler Z06 setup just to get the dual mode muffler sound. Just buy Z06 mufflers, cut off your stock mufflers and weld the Z06 mufflers to your stock over axle pipes. The Z06 mufflers are the same size at the inlet, 2 1/2", as your stock pipes or NPP.

 

Z06/ZR-1 have 3" over-the-axle pipes. NPP has 2.5". There is also the alignment of the over-the-axle pipes with the H-pipe if you go the 2.5" route - not sure of the year when this changed. Since you have an M6, the 3" pipes will fit around the transmission (not the case for auto cars, at least without some fab work) but you need the right combination of H/X-pipe to cats to manifold. https://www.corvetteforum.com/forums...ase-coupe.html

You can do what Rick T is saying and have your 2.5" over-the-axle pipes welded onto Z06 mufflers so it matches to your existing H-pipe. The last two sets I have seen on the parts-for-sale have had them cut to get them off the car easier.

Another thing to consider is the internals changed. My understanding is the NPP, ZR-1, and 2011+ Z06 mufflers are the same (except for the over-the-axle pipes). The 2007-2010 Z06 mufflers have holes in the "un-muffled" pipe (w/ the butterflies), and solid for the muffled. The early Z06 mufflers are louder in the quiet mode and quieter in the loud mode than the NPP/ZR-1/Later Z06 muffler. Hence the "muffler mod" where the early Z06 mufflers are cut open, the "loud" pipe replaced with a new piece w/o holes, and the mufflers re-welded.

Then you need a retrofit kit; There is NPP-in-a-box which is sold through a couple different retailers, or NPP-Vacuum-Retrofit-Kit from SunsetOrangeCreations. The sunset kit is more expensive and harder to install but does not require drilling. Also not sure how the sunset kit will get it's vacuum as the LS2 doesn't have the stock port that is used on the LS3/7/9. The NPP-in-a-box requires drilling into the passenger side rear storage compartment and gets it's vacuum at the MAP sensor.

http://www.nakidparts.com/id78.html (I believe this is the manufacturer, but a couple of the vendors have better deals on this ATM).

http://www.sunsetorangecreations.com...trofit_kit.php (Only available from him as far as I know.)


I bought '13 ZR-1 mufflers and a set of ARH headers w/ 3" X-pipe and NPP-in-a-box. Should be getting it all put on this weekend. I'm still considering returning/selling the NPP-in-a-box and getting the Sunset retrofit as it seems like a better solution (albeit at 2x the price). Edit: car is an '05 M6.

 

Couple of mistakes in your above post.

The Z06 mufflers have a 2.5" inlet (a 3" pipe to the inlet but the muffler has a 2.5" inlet), the same as the NPP 2.5" size.

The Sunset Orange Creations gets its vacuum from the same place at the back of the manifold as any of the kits.

Sunset Orange Creations is comparably priced to any of the Vendors for the same mods. He is the Manufacturer, the Vendor and the salesperson for SOC. The NPP in a box manufacturer isn't a Forum member and all his parts are sold by other Vendors that are Members.

 

Good luck!

 

Thanks for the clarification on the NPP and Z06 NPP/bi-mode mufflers. I was wondering why the mod was necessary on the Z06 NPP and why they were so much cheaper and easier to find than the std NPP exhaust.

I want to put the NPP/Bi-mode on my 07 A6 convertible. I know that the Z06 mufflers neck down to 2 1/2". So my question is whether I can just cut off my OEM mufflers and weld or clamp the Z06 NPP in their place? Then I could use the NPP in a box to control them. But how do I get the vacuum to run the butterflies since my LS2 has no port?
Thanks for your help.


I'll ask you the same question as I asked above.
I want to put the NPP/Bi-mode on my 07 A6 convertible. I know that the Z06 mufflers neck down to 2 1/2". So my question is whether I can just cut off my OEM mufflers and weld or clamp the Z06 NPP in their place? Then I could use the NPP in a box to control them. But how do I get the vacuum to run the butterflies since my LS2 has no port?
Thanks for your help.

Another question for both of you is if the NPP exhaust has a drone when closed? I assume it will in the open position.

 

My 08 came with the NPP and it has no drone when closed, where did you hear this. Being an auto it is harder to control the drone when opened, I switched my complete system except for the mufflers with one from a ZR! and the sound has improved a lot.

 

I assume your comment is to me. I haven't done any research on the NPP and drone and so I just guessed that it did not drone when closed and may drone when open. Since I've never asked anyone about it I figured I should ask instead of assuming.

 

I have an 08 M6 car with factory NPP. There is definitely no drone when closed - it's very quiet by performance car standards. Even when open (fused pulled to keep it open at all times), drone occurs in a narrow range of throttle openings/RPMs, and it's not what I would consider intolerable.

 

I have had both on my car, the NPP sounds the best between the two in my opinion.
There is a little drone when open, but not too bad. Nothing like bullets or the GHL systems.

You really can not go wrong with the NPP, just get an 08 system to match the pipe routing for your car.

Good Luck,

DJ

 

[QUOTE=J Vette;1587769497]Thanks for the clarification on the NPP and Z06 NPP/bi-mode mufflers. I was wondering why the mod was necessary on the Z06 NPP and why they were so much cheaper and easier to find than the std NPP exhaust.

I want to put the NPP/Bi-mode on my 07 A6 convertible. I know that the Z06 mufflers neck down to 2 1/2". So my question is whether I can just cut off my OEM mufflers and weld or clamp the Z06 NPP in their place? Then I could use the NPP in a box to control them. But how do I get the vacuum to run the butterflies since my LS2 has no port?
Thanks for your help.

Yes, you can cut the stock overaxle pipes and weld the Z06 mufflers on. No way of clamping since both are the same diameter.

Sunset Orange Creations has a huge choice of controllers and can show you where to get the vacuum source. Your LS2 has a vacuum port at the back of the intake manifold.

 

Wow! Thanks for the info. I knew about the controllers but didn't know about the vacuum port at the back of the intake manifold. Thanks alot. That will make things much easier.

 

Check out the DMH cutout install on my 2006 C6 Corvette.

Douglas in Green Bay

 

hmmm yes it was directed at you but.....after re reading your post I see you phrased it as a question and at first I thought you were making a statement. sorry bout that chief.

 

ZR1 exhaust or late model Z06s are the best, another great option is the B&B Fusion's . I have the ZR1 complete setup on our 09 Coupe and it rocks

 

My 2014 LS3 Camaro got an LG Performance super pro 1 7/8 header install with LG 3" exhaust into GHL no-drone 2.5" inlet mufflers. It's nice and quiet when I drive it easy. On a calm night, you can hear it MILES away when I quickly it up to 6000 RPM while sliding sideways through 3rd gear. The stock Pirelli P Zero tires can't handle the car when it was stock. Let alone the 40 RWHP gain from the exhaust and tune from Anthony at LG Motorsports. A few 10ths under 410 RWHP isn't bad at all for a car still running a stock air box.

 

He is asking about an exhaust for a corvette, the car construction and exhaust placement makes the comparison irrelevant. The GHL exhaust on a Vette drones worse than bullets, I have had both.
But, glad that you are happy with yours, finding the right exhaust is sometimes quite painful on the wallet until you find what makes you happy.

 

I don't have a GHL exhaust - I have GHL 2.5" inlet drone-free mufflers installed on reducers to the :G 3" full exhaust. The GHLs are NOT drone free. The LG 3" mufflers MIGHT be the way to go. In any case, the drone WILL go, one way or another.

The folks at LG know their stuff and will steer me in the right direction. Lou has forgotten more than I'll ever know about chassis/motor tuning. LG Motorsports DOES get their custom built short blocks from my old buddy, and Dallas street racing legend, Kim Barr.

Yup, I've been doing hotrods/racecars since the late 60s and motorcycle clubs since the 80s.. '32 Fords to chop-top Mercs, I've built worked on them. My old girlfriend from high school had a father the, with a partner, built in their garage a car that qualified and raced in the Indy 500 in the late 50s.

FYI - comparisons are NEVER irrelevant. A fellow no longer with us once told me that. He went by the name, Smokey Yunick. I met him while picking up a set of heads at Shepherd Racing Heads in Arlington, Texas. Reher-Morrison's and Shepherd's shops were only about 15 miles from where I lived as a kid. Sweeping floors at shops like David and Buddy's as well as Lee's paid off incredibly well. The "secrets" I was told about were not for the public, but for friends and folks those legends trusted. I swept floors and took out garbage for 2 years before I became part of the "group". I was given tech advise money couldn't buy at ANY price.