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C6 Corvette ZR1 & Z06General info about GM’s Corvette Supercar, LS9 Corvette Technical Info, Performance Upgrades, Suspension Setup for Street or Track
Looking for a few answers. I would assume that this mod makes the muffler louder with the valves open but what I'm concerned with is if it's louder when they're closed. Or is it the same or quieter with the valve closed. Any opinions welcome.
The previous owner of mine had done this mod when I bought the car so I can’t say for sure - but it technically shouldn’t be any different when closed than before. I can say that when closed mine is significantly quieter and there is no drone. About the only time I close mine is if I’m on the highway anyway.
Did the non-3in muffler mod on my 2006 Z06. Definitely louder with the valves open. Car certainly is not any louder with the valves closed and, if anything, the drone with the valves closed got a little better after the muffler mod.
if you can do the work yourself, it’s the best economical mod you can do for your car. I have done 2 and don’t think I spent more than $20 per. by the way I removed the blanket on both. I love the “wraspy” sound w/LT’s once you get above 5k rpm @wot. pure 427 heaven...
This is how I did mine. I added perforated sections to BOTH bypass tubes. Very quiet when closed, loud with butterflies opened. As Mick likes to say "get down".
I put the fiberglass back in as well. My mild to wild is a switch.
My 2008 Z06 is slightly louder with the valves closed. My car retains the OEM cast iron exhaust headers. With the bimodal muffler valves closed at highway speed, there is no drone. Note that the bimodal valves will be open during engine starting, as they are powered by intake manifold vacuum. As a result, the exhaust makes a loud "bark" during each startup.
Note that the fiberglass packing was left in the center section, at my direction. There are some folks who opt to delete this packing during the muffler mod procedure.
Mine are a little louder with the valves closed, more of a whispering growl ( actually sounds more like it should stock ). I think this is due to the 3" pipe not being completely sealed to the bulkheads in the muffler. the original 2 3/8' pipes were pressed in and fit the bulkheads tighter. I also opted to put the glass packs back, not as much for sound but to help keep vibration down to help prevent cracking.
And also the sound will be totally different with headers and hi flow or no cats!
Pretty much the same in quiet and much louder when open. Pops on decel are amazing. For sure do it, no brainer mod.
I wouldn't call them "pops" any longer, I'd say it sounds like a gunfight. Super loud and super awesome. WAY louder than stock mufflers when open. So much so, that I'll set Dashlogic to quiet mode so they don't open at all when cruising, because it sounds like VTECx10 every time I'm over 3500rpms
Mine are a little louder with the valves closed, more of a whispering growl ( actually sounds more like it should stock ). I think this is due to the 3" pipe not being completely sealed to the bulkheads in the muffler. the original 2 3/8' pipes were pressed in and fit the bulkheads tighter. I also opted to put the glass packs back, not as much for sound but to help keep vibration down to help prevent cracking.
And also the sound will be totally different with headers and hi flow or no cats!
My modded OEM mufflers kept the glass packing, but this still was not sufficient to prevent the baffle cracking. And I have OEM cast exhaust manifolds as well.
I have done many versions of the muffler mod. the basic muffler mod that everyone is familiar with is louder when closed and had more drone. Mike44665 version of the muffler mod would be the most efficient in less drone and very quiet. I personally do not like the traditional muffler mod. if you have no interest in doing the 3" mod then Mike's version is the way to go.
03-31-2018, 03:57 PM
Those with the "muffler mod"
