ayousef

I had goodluck with these on my cousins whipple charged 2012 Camaro SS, but not this time.

For those who havent seen my exhaust thread, I have a true dual exhaust, with Dynomax ultraflows straight through followed by Dynomax VTs straight through on each side. I also have a cam with 4 degrees of overlap in case that might have something to do with it.

The damn valve makes a very obvious/loud clunking noise especially during cold starts, but will also do it at a hot idle at times, of course nothing at cruise.

I got my mufflers from Keystone, and wondering if the old batch of mufflers is still out there somewhere because if so then this would be a VERY bad move from Dynomax, not pulling out the inventory of bad mufflers from whoever sells them.

I did not look through the muffler to make sure if it had the padding under the valve, and there is absolutely no way i could see that right now since the entire exhaust is welded from before the x-pipe to the tips, so id have to cut it just to look through.

VERY dissapointed, I will try to smoothen out/raise the idle but if that doesnt solve it, im throwing the VTs in the trash. I spoke very highly about the VTs to my local exhaust shop that has ALOT of business throughout this part of the world, they loved the dynomax VT design so much and wanted to know if Dynomax would sell them the VT mufflers minus the embossed Dynomax VT logo but all of that went out the window as soon as we fired up the motor and the exhaust began clunking unfortunately.

Gbody6liter

I remember when those first came out, I had a bad feeling about that spring loaded valve. It's dumb IMO because one, it's very prone to vibration and two, it's almost just as bad a restriction as the baffling in a Flowmaster. Sorry to hear you're having such issues bud. Here's to hoping you get it sorted out.

ayousef

just when I thought this was gonna be my LAST exhaust...

Ill get a video of how bad this is during a cold startup so no one thinks im exxajerating or something.

CC05

iTrader: (2)

Big case Magnaflow and resonators/bullets. The reason so many people have it, is because it works. Try it. Makes sense that the flap would malfunction at cold start-up, because of the cam...maybe it doesn't. Either way, I've had two Dynomax and hated them. Junk mufflers, IMO. Best of luck with the fix.

ayousef

I have two dynomax ultraflows right before the VTs, and I also used the VTs before and I really like the quality but im not sure what went wrong this time?

Im really fed up swapping exhausts out, if I ever do Ill build one of my crazy exhausts that I used to do in the past, vaccum muffers, RPM/throttle actuated goes from dead silent to insanely loud in an instant, but again too much money spent.

What im getting to is that when the mufflers are cold, it does this clunking sound, regardless of cam lope, I try raising the idle to 1200rpms at a cold startup just to see what happens to the sound and it doesnt go away, the mufflers need to stay hot for them not to produce any sound.

Other than that it sounds really nice at part throttle, and the mufflers work even better at WOT, where it gets really quite.

Still waiting to hear back from Dynomax, but I simply cannot take the exhaust apart, send them the muffler to inspect it yada yada, it costs more than the mufflers themselves just to SHIP that thing one way...

BOSS302

I'm betting you got the older version. I've got the vt cat-back and it doesn't rattle at all. I'll see if I can manage to get a few sound clips later.

ayousef

mine definitely does not rattle, but it makes a metal to metal contact sound thats pretty loud when the muffler is cold, I know this shouldnt happen.

Also i was thinking it would work much better on a y-pipe set-up since you always have exhaust flowing through the ypipe unlike a cammed true dual setup which gets "choppy"

BOSS302

"Rattle" wasnt the right word, but the metal to metal pop sound you described was very common on the first generation VT mufflers.

ayousef

dang I thought those were off the shelves by now but what do I know?

Im shooting a video tomorrow and sending it to Dynomax, ill see what solution they have to offer.

CC05

iTrader: (2)

How thick is the flange itself, inside the muffler? I'm definitely in to hear what the problem is. It's unfortunate that you're on the other side of the world, because that alone burns a lot of cash in the situation at hand.