fastdriver1

Been thinking of doing the mod for a while. I had installed a switch to open the valves and it was OK but not great.
Yesterday I did the muffler mod and I have to say that it was one of the best spent 3.5 Hours I have done in mods on this car. The sound difference is remarkable! And having the ability to switch to 'stealth' mode for highway and trips is just the best!
Found that it was necessary to remove the 'H' pipe first (at least on this car) before removing mufflers
Removed the left muffler with no problem.
The right muffler was becoming a problem and I had no desire to drop the cradle so I just dropped the muffler down and did the mod in place with no problem at all.
I used the NAPA stainless band clamps and re-installed the 'pillows' before welding the cans closed. A little grinding to smooth the welds and some flat black high temp paint.
A great mod and a $1400(average) saving with the ability to return to quiet for trips.
I'm a happy boy!

08Z06JSB

Awesome - Congrats on the new "controlled" sound.

Scuba_Steve

Wait till you add headers and a nasty cam

ufaj26

To the OP: Congrats on the mod.

To Scuba Steve: That thing sounds nasty !!!

03 Z-oh-6

Is it A LOT louder? I've been thinking of doing this, but I don't want it ridiculously loud!

veech

I think it sounds better than my Corsa's did

Scuba_Steve

A buddy of mine has the same cam as me, catless headers and BB Fusion mufflers with the valve. His drones a lot more then mine even when the valves are closed and mine is actually louder when the valves are open but no drone when they are closed. I think the muffler mod is the best mod you can do for these cars if you want more sound .

jwlowtheman

I just did the mod last week you will not regret it in any way its great. it is not noticicably louder under normal operation but it is a world of difference when valves open it sounds like the z should sound

augydog

Best mod I ever did

augydog

STLBLUES

Anyone doing the mod in the future should also cut out a large square in the inside wall that is closest to the tips. When the exhaust is closed it lets pressure through 2 small holes that go into a closed chamber. The exhaust cant escape so it blows out the wall and you will get a nasty humming tin sound from the crack vibrating.

Wish I had pics. Look inside the tip that has the valve and you will see the 2 small holes, cut the inside wall to expose them. The exhaust note will not change in loud or quite. The 2 holes will now release into the muffler can.

Some stock unmodded z mufflers are breaking the welds and the wall also. I do not know if the NPP has this problem. I have only welded on bi-modes from z06s. NPP has perferations inside the tips and Z bi-modes do not

blackvetterzo6

I dropped the cradle to get that right side out. That was the only pain. It's funny because it went in so easy after the mod. It is a awesome mod. I get compliments all the time on the sound of the car, the cam really makes it bad azz.

03 Z-oh-6

I wonder if many people have done this?

STLBLUES

I think I am the only one that has so far. I will try to post some pics over in the c6 z sticky and here. I had to come up with a solution after 2 sets busted out the wall (baffle). A friend of mine has a stock z with the wall (baffle) busted out.

I think one reason mine busted is because I have my switch wired to open or close the cut out at any RPM. I can run full throttle in all gears with it closed or open. Closing the valve and running to the redline is part of the reason they bust out. This doesnt explain the stock Z problem.

fastdriver1

Good Job! Heard the car before I saw the car.

Fastdriver1's wife

wags

I love the muffler mod-best mod so far!

fastdriver1

Damn!
She found me!

RichieRichZ06

I wish I had. One of mine is cracked inside and sounds like crap. It rattles really bad from 1,900-2,500 RPM which unfortunately is right where you a e most of the time.

diverdan

Am I understanding this correctly: If you close up the perforations in the center chamber (doing the muffler mod), you are blocking the route for excess pressure when you run with the car in mild mode?

If someone could post a picture showing where this additional overpressure hole needs to be cut, it would be great, as I am having a little trouble visualizing it.

03 Z-oh-6

STLBLUES

NOTE.... My mod is not pictured. Picture is for reference only.

With the valve closed (modded or stock) the valve side exhaust escapes out of 2 small holes back into the right chamber. If you look into the valved Z06 muffler tip with a flashlight you will see 2 small holes in the side of the pipe.

If you cut a large hole or square into the right chamber wall that is exposed in the picture you will see the exhaust can now escape into the center of the muffler. Basically the right wall inside of the can needs to have a hole cut into it.

I know pictures would help but if you look the muffler over you will find the 2 small holes and discover the exhaust pressure from them goes into a small closed chamber. This chamber has no exit so the wall ends up bursting. Corvette power is hard on mufflers!!