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ZZP Exhaust Drones...Anyone Use Dynamat in Trunk?

J

Jason E

New member
So I just installed my ZZP 2.5" catback and catted downpipe. I thought for sure with a cat, resonator and mufflers, I would be ok...but the drone is awful under light throttle. Cruising seems to be ok...haven't driven it far yet, as I'm at work and installed it at work this morning.

Has anyone used Dynamat or Dynapad in their trunk to reduce exhaust drone? I'm getting conflicting info on this. I'm planning to use both if it'll help. The tone is awesome...there's just too much of it...but I don't wanna go back to stock after just buying this thing. Any help is appreciated....
 


Usually their mufflers from past reviews have sucked; same with the resonator. If you can find a stock replacement or Walker resonator, it'll really help without having to dynomat everything.
 
Most tend to add the biggest resonator possible.

I did mat the whole trunk, back seat etc etc and while it quieted things down overall (not exhaust related reasoning), .... it'll never quiet down a 3800 exhaust enough to make it worth the cost.
 
Is DoD still active?

That will cause the helicopter drone noise in the cabin on LS4 cars. You could add a 2nd smaller resonator too so cancel out even more of the drone.
 


I don't think any connections are leaking, as I don't hear any ticking or see anything funky. I just had the dealer I work for install it yesterday...its just loud as hell and makes your ears tingle.

I still have my stock resonator because a tech swiped it before they threw the catback out. Its 2.5", just like the rest of the exhaust. Should I swap the ZZP res with the OEM res? Is it worth the effort? Some people are telling me to put a long Magnaflow muffler in place of the res, but I'm afraid that won't cancel out the frequencies causing the issue...
 
A Magnaflow 12641 is what Will OverKill says he always recommends and has success with, I'm sure they have a 2.5" with the same overall dimensions. From http://www.grandprixforums.net/threads/88203-2-5-or-3-inch-exhaust post # 18.

I have been planning a 3" cat back using ZZP piping without their mufflers or resonator. Using the Magnaflow above and Borla 400495 Pro XS mufflers. I'm hoping that will work well. Choices for quiet mufflers get smaller when you are wanting to stick with SS. I'm wanting all SS from headers to tips.

I would pay attention to the overall diameter of the resonator and try to get as large of a body as possible. Which means it will have more sound deadening material (packing). I know that the GMPP mufflers that Borla made for GM the only difference in the sport muffler compared to the touring was the touring had a larger diameter body ( same pipe diameter, same length) to make it quieter.

ZZP I think lists their mufflers as chambered mufflers which I associate with Flowmasters (right or wrong) and I've never heard a Flowmaster sound good on anything that wasn't a V8, unless you like loud & raspy.
 


Back in my mustang days, my understanding is drone is caused by the 2 mufflers being the same ans they are producing the same note that are just slightly outta tune from each other. Im sure other v8 owners have noticed driving by another v8 car the notes start to modulate as you get near each other they eventually match and stop as you keep going. I know some mustang guys actually used 2 different size or style mufflers and it did work
 
The only true way to remove resonance is to identify the frequency it is eminating at and install a Helmholtz Resonator to offset the frequency. Other than that, you can quiet it, the Vibrant Ultra Quiet is great, and you could install 2 in tandem... I haven't done that myself, but they're only 12" long I think... Lol
 
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