Not the same. He's trying to get loud exhaust for cheap, we're trying to quiet down the stock exhaust to pass sound at certain tracks.

 

Ya we both need to find someone with some background in exhaust theory it seems. I think I’m just going to y the two pipes together.

 

The "muffler mod" is normally done to C6 cans. and makes the Loud mode louder/deeper, and retains the same stock quite side.

The C6 loud side has perforations in it & and the 4 round holes to flow when valve is shut, when open most gas flow out tip, with some noise being soaked up through perforations and stuffing. Shut the vavle, and all gas has to flow through the holes, and the perforations and into the to the other chamber and out the other tip. When the mod is done, you seal off all the perforations, but the 4 holes have to be left so when the valve is shut there is somewhere to flow into the other chambers. C6 Zr1 npp is like this from factory

On the C7 the loud side is already solid as you can see in the pic. no perforations to seal off. loud side is solid pipe with 4 escape holes for when valve is shut. If your goal is to make the car quitter. you could introduce MORE holes into the Loud solid pipe. THus letting more gas escape into the other chamber witch valve open. basically backwards muffler mod.

 

So the other side of the coin, if I want it louder. Seal off the 4 holes and y the two pipes inside the chamber essentially making straight pipes. Or maybe an H pipe between them. Don’t think anyone has done that yet.

something like this:

 

if you seal the 4 holes, the valve can not ever shut. This ill be like a banana in the tail pipe. No exit.

can you cut the muffler open, connect the 2 pipes, and stuff like you drew out? sure. but that's a lot of work, for just strait pipes. if that's your goal, be a lot easier to just remove muffler, Y each pipe to the 4 tips. Working in side the muffler, re welding the thin cans, all a pain vs new pipe.

the good thing about the stock set up is 99% strait pipe on the loud side, and then a factory quite option. If the open side is not loud enough. Add headers, no cats, the factory set up is awesome like that and VERY big difference in sound with the touch of a button.

 

Well the idea is that if I do what is drawn I could close the valve and it would just divert the flow through the H or Y pipe that I would add.

the NPP would still be functional just different in the exhaust route. I’m hoping this would increase the volume some but it’s just a guess right now.

yes it’s a lot of work but I’m wanting to use my welder and learn to do some of this stuff myself. Also I’m using the Z06 mufflers so I’ll be removing the afm valves as well and going with simulators.

if I screw it up it should be easy enough to just cut off the mufflers as you suggested and go straight pipes. If that doesn’t do it for me then I still have my stock mufflers and go back to how it was or go aftermarket.

im in CA so I can’t do headers otherwise I would just leave it alone and the headers would get me the volume I’m looking for. So is it a waste of time? maybe, but I like to tinker so if it’s enjoyable at a low cost I’m ok with that.

Thanks for suggestions, hoping for more before I start cutting!

 

Who knows maybe I’ll come across one of those WTT threads where someone got an exhaust they think is too loud and will want to trade. I have a lot going on right now so I’m not going to start this for a few weeks at least.

thinking of getting a cheap Amazon plasma cutter to play with too. I like getting new tools for projects and learning.

Either way, it’s more for fun than anything.

 

Your correct with your drawing shutting the vavle will route it to the other tip. but its still just a single strati pipe. or vavel open with one strait pipe, with a H pipe and another open tip. I don't think it will make the car louder, just make quite mode louder.

That being said spare muffler, and wanting welding practice, have at it and post some results. Love some good trial and error / experimenting. I agree with out headers its not that loud. but I always run headers on my own cars.

 

So now it time to bolt them on and see how it sounds

 

Wish you luck. post results for sure

My thoughts:
The Loud side will be slightly louder with the 4 hole shut Slightly.....
the quite side will now be louder then before, and less dramatic change when opening and shutting the valve.

 

On my C7 I chose another route----I did a "muffler delete" and installed the dual quad 4" tips from Flowmaster Being that this car has 4 cats it is not as crazy as you might think
Surprisingly It is not that loud or annoying When it 1st starts it barks nicely but then quiets down
I can still hear the radio and talk on the cell easily While cruising it has a nice mello v8 sound but when you hit the loud pedal it sounds amazing !!
I did not order this car with the NPP exhaust --as I thought $1200 was ridiculous
Total cost of the muffler delete
$80 for the Flowmaster tips
$100 labor to install

JMHO

 

Awesome looking WINDOW Mod! Now you can Watch the Exhaust FLOW!

 

Sorry I don't have pictures but I'll explain what I did to my Camaro NPP to pass sound at NCM. My car was a Callaway SC630 with primary cat deletes, I still had secondary cats. I did these modifications before heading to NCM in case I needed to quiet it down. I removed the valve actuators from the muffler and drilled holes through the valve "rotator" i guess you would call it, that lined up with the slots you see on the actuator brackets. When I blew 105db and got black flagged i dropped the muffler and rotated my valves to the half shut position that my holes lined up at and inserted self tapping screws to hold them halfway closed. This still let some flow through the straight pipe section but sent more flow through the muffled section and I passed sound the rest of the weekend. I already had the fuse pulled so no CEL because i usually ran a Hooker Blackheart track exhaust with no mufflers or cats, but I knew I had no chance in hell with that exhaust so that's why I had my factory NPP back on. This is a hell of a lot easier than cutting open the can and drilling extra holes then welding it back together and not knowing if it will be quiet enough.

 

That’s good news. I’m installing it tomorrow and will report back on how the npp functions at reducing the volume with my mod

 

Excellent idea! I hadn't even considered forcing the valve to be at some intermediate position. I guess I was just thinking that since the valves open during WOT even in stealth mode I needed to explore other options. I like that method much more than any other option I've been considering. Thanks!

Alex

 

Geeez I must be getting old cause my C7 with it in the track mode and the driving mode in sport the exhaust is plenty loud for me. I guess thats what being almost 70 is like. I pulled the fuse in my 16 Camaro but it wasn't as loud as the C7 exhaust. Go for it and make it loud.

 

 

Who makes that lift ?

 

 

I was going to post a video of the sound but for some reason I can’t get it to upload