Serhan'sGarage

Im looking to install a complete Z06 exhaust system for my LS2 and i have a few questions.

The Z06 mufflers i found are the NPP dual exhaust version but my car does not have the NPP option. Will this muffler work..basically will the wxhaust remain open all the time or do i need to purchase additional components.

It a direct fit....i nust need the Z06 manifold gaskets and o2 sensor extension is this correct.

How is the sound? Any drone with this set up on my stock ls2?

RicK T

First, to be picky, Z06 mufflers are "dual mode", they are not "NPP", similar but different animal in terms of sound. Z06 mufflers are quieter, more "mellow" than NPP's. If NPP style sound is what you want, you will have to do the Z06 muffler mod, where you cut the cans open and weld a solid pipe around the perforated pipe inside. Just sayin'.

If you install the Z06 mufflers and do nothing else, then yes, the valves will stay open all the time. If you want the mufflers to remain dual mode you will have to supply a switchable vacuum source, most just buy one of the aftermarket "NPP in a Box" kits.

Z06 mufflers do not drone.

Some threads with discussion and pics on doing this on an LS2:

https://www.corvetteforum.com/forums...-manifold.html

https://www.corvetteforum.com/forums...-2006-ls2.html

https://www.corvetteforum.com/forums...ust-to-c6.html


Z06 muffler mod:

https://www.corvetteforum.com/forums...with-pics.html

Pics in post 5 and 11:

https://www.corvetteforum.com/forums...6-muffler.html

Dcasole

You will need to purchase a "NPP in a Box" it will have everything you need to control a bi mode or NPP exhaust

As far as drone , when you want it loud, press the button when you want it quiet , press the button

When it's closed it is as quiet as a stock vette which is pretty quiet . When open ...... they sound really good ..

Especially with headers

I personally like the sound of my NPP'S over the BI Mode

HOXXOH

You only have your State of residence in your profile (I suggest you add more). So now I have to ask what year is the car and what trans does it have? I also need to know what year Z06 the mufflers are from?

There's a bit of a difference of how to make it all work, but without knowing the above, no one can provide the correct answers.

Serhan'sGarage

Mine is a 2007 manual ls2. The Z06 system im looking at is from 2007. Thanks.

HOXXOH

Thanks for the update.
It'll be a bolton and the only thing you'll need are exhaust manifold gaskets to the head and to the downpipe/cats. I say need, because the Z06 3" pipes are a very tight fit over the axle, they don't provide maximum power, and you won't have a way to control the flaps.

You can strip back the tape on the wiring harness to get enough length to plug in the O2 sensor. Be sure to retape the remainder to look like OEM, since the CA inspector might question an untaped harness. Also make sure the O2 wiring is secured away from the exhaust manifolds. Use black wire ties to be inconspicuous.

You can reuse the Z06 donuts between the downpipe/cats and the H-pipe.

If you're looking to get the most power, it's a little more involved and requires cutting, welding, and buying a reducer.

There are several ways to control the flaps for sound that range from less than $20 to well over $200. Run them open for a bit, since maybe you'll like it that way and it costs nothing.

RC4G

Keeping in mind that the OEM Z06 cans neck down to 2.5" as they enter the mufflers what are you basing your statement that "they don't provide maximum power"?

Do you have anything to support that claim? Back to back dyno runs, same car same dyno? My experience replacing my Grandsport 2.5" headers/cats/x-pipe and exhaust with 2011 Z06 system showed an improvement in HP, not a reduction.

It's just that I've heard that statement before but no one has ever been able to show documentation supporting it. When pressed, everyone always responds with the old school "HP requires back pressure ..." statement but I've never seen any dyno runs to support it.

FWIW, this is a great video comparing 2.5" versus 3" versus open headers using the same motor, dyno and tubing lengths:

HOXXOH

The video is using a highly modified 454 ci motor, which is not even close to a nearly stock 376 ci LS3, nor could it be compared to a 500 ci top fuel motor.

I never said there would be a reduction (your words) in power, but only that full 3" pipes on a bolton won't make the maximum available.

And no, I don't have dyno documentation, since dynos are only a tuning tool. Any back-to-back dyno pulls where parts are being swapped are worthless unless there is tuning included to allow the maximum performance from each part being compared.

Maybe that my car with Z06 manifolds and 3" H-pipe that reduces to 2.5" before the over-the-axle pipes lead into Z06 mufflers, is the only LS2 or LS3 car that ever ran 10's on the tech forum's performance list, might be the documentation you'd accept.

Then again, you could open most any physics book and read about the ideal gas law and with a little understanding of fluid mechanics be able to do the calculations related to heat, volume, and speed.

RC4G

Why the panty twistage? I asked a simple question whether you had any definitive proof that a 3" exhaust (although the argument seems really moot considering Z06 exhausts are not 3" all the way through anyway) will never make as much power as a 2.5" exhaust.

Regardless ...

So your answer is no, you don't anything at all that will validate your statement that a 3" exhaust will never make as much power as a 2.5" exhaust.

Why even bring 1/4 mile times into the argument? Maximum HP is just one of many factors involved in lowering times, including but not limited to track conditions, driver skill, and traction (just to name a few).

I do have back to back runs (same car, same day and same dyno) with a basically stock LS3 (CAI only) swapped out stock Grandsport 2.5" headers/cats/and x-pipe for a stock Z06 3" system showing a HP improvement without any tuning modifications.

Maybe I missed the part where the OP was chasing maximum HP on an all stock motor. Wasn't his original question simply asking about how a NPP will sound and whether he will need new gaskets?

HOXXOH

And again, you missed the point. I'm merely stating that a full 3" system on a LS2/3 will not make as much power as a system that reduces the 3" pipe to a 2.5" pipe prior to the over-the-axle pipe. Your swap only compares a full 2.5" system to a full 3" system. You do have a reduction to 2.5", but it doesn't happen until it gets to the muffler, which is too late to maintain the velocity that the LS2/3 heat and volume produces. The Z06 engine creates more heat and volume, so the velocity is maintained well enough to reach the 2.5" reduction at the muffler. It's simple physics.

I brought 1/4 mile times into it, since my dyno HP doesn't reflect the true HP the engine is making. You may find it strange, but my dyno HP has dropped each time I installed higher stall converters, yet my MPH has consistently increased, which relates to HP. You'd be hard pressed to find a C6 with under 400 dyno HP that runs 126 MPH trap speeds.