Vetteguy055

I have a 2007 Corvette, base model. I've had it just a few months. Wondering why I have such a loud, almost constant drone sound. Very loud - almost objectionable. Stock exhaust; no CAI, no headers, no mods - all stock under the hood. I owned a C-5 prior to my 207, and never had this drone issue. Any helpful thoughts are appreciated.

Must_Have_Z

Visually inspect your mufflers for any cracks or holes first. Also check all your piping from your exhaust manifolds back - make sure the connections are all tight and the tubing looks solid.

Vetteguy055

Thank you Must_Have_Z for your speedy reply and good advice. I'll take it into a muffler shop soon. Thanks again!

Homer3D

Since you bought it used, it is possible the previous owner modified the exhaust. Was it loud before you bought it? If it truly has stock exhaust it should have absolutely no drone. I had a 2005 where I did exhaust, headers and cam. The drone was INSANE but completely went away when I put the stock muffler back on. The previous owner might have also done the stock muffler mod, which keeps the stock muffler but cuts holes within the muffler to make it louder.

Vetteguy055

Good points. When I test drove it prior to buying, I did notice the drone, but not as loud as it is now. Because the car appears stock, I'm presuming the prior owner(s) did no mods, ie: cam. I see no headers and I know the mufflers are good - no holes. Heck, the car has only 39K miles. Yep, a trip to the muffler shop is necessary. Thank you Homer3D.

Ahrmike

Does it have an NPP system? (can you see little valves above the quad pipes?)

Vetteguy055

No, on the NPP system. Thanks Ahrmike.

<< PROBLEM DISCOVERED >> Took it to a muffler shop this morning. Tech looked at the mufflers and said they are FLOWMASTER. He said, likely 40 series. Well no wonder I have super loud interior drone! I'm thinking of going with FLOWMASTER Super 50 for no interior drone.

~STOLEN~

time for corsa sports!!!!

Homer3D

If you are planning on keeping the rest of the exhaust stock, take a look at the Magnaflow mufflers 14336. I had them on my 2005 when everything else was stock and I loved the mellow tone. But after long tubes + high flow cats + cam, the drone was way too loud and I ended up putting the stock mufflers back on.

farmington

Ahrmike

Oh, Yeah. I had those on my Camaro a while back. They drone like MAD. They sound really good when you're on it though.

kozmatic

I just installed Borla S Type II and it has NO drone at all. That's with BTR Stage 4 cam, headers, X Pipe, high flow cats and 3" exhaust. I can't say enough about how Borla engineered their new exhaust to be so aggressive yet no drone. I promise there's no Flowmaster on the market that won't drone.

ONEBADZ

Vette_Fan

I've a stock 2008 vert with NPP. It has drone at ALL speeds, even in town at slow speeds. 33K miles. All stock....

Homer3D

Wow, you must be very sensitive to drone. For me the NPP open sounds good while closed is way too quiet. I don’t issues with drone at all with the stock NPP. I wonder if it sounds different with a convertible (I have the coupe).

HOXXOH

I'm guessing what you call drone is actually volume, since drone is a constant pitch sound created by a short range of exhaust pulses. Those pulses are in the 1400 to 1700 RPM area. Of course, if you always drive at speeds where the engine is in that RPM range, drone will be there. It'll always be gone above 80 MPH, no matter what gear you're in.

thodgen

You might want to check that NPP is functioning correctly. My NPP is completely silent normally, but lower when you give it lots of throttle. I"ve actually installed Mild to Wild Adapter, and yes, there is a bit of a drone when I have NPP turned off, which gives me open exhaust full time, but goes to completely silent when I turn it back on.


BTW, I love the Mild to Wild Adapter - which installs in about 5 minutes, with remote control of NPP exhaust. About $70. Highly recommend it!

MTPZ06

If you're not a fan of drone, I'd move away from the Flowmaster mufflers altogether.

techmonkey

I agree with the other replies regarding the npp. When I fist got my vette the previous owner had removed the fuse. It droned badly at low rpm on the highway. I put a mild 2 wild on it and it's almost too quiet when it's engaged (the same as having the fuse plugged in).