VE Sportwagon + KPM Exhaust Drone

[unitdiplomacy]

Hi Guys and Gals,

I know this topic has been covered quite a few times, however it is difficult to find the answer i am after.

I recently Purchased a 2010 CalaisV Sportwagon AFM and after months of research i came to the conclusion that KPM was the way to go with a "No Drone" Exhaust, so i settled with the 2.5" Cat Back, as i live near Canberra i was directed by KPM to get the Exhaust installed at Roadway Exhausts, they did an okay job, it had to go back as the passenger side muffler tip was making slight contact with the rear bumper mold, and the cross piece underneath (im assuming its to catch the exhaust / driveshaft) was making contact and rattling over bumps.
So after a bit of driving on the highway i am not entirely happy with the cabin noise, i know its difficult to reduce because its an auto a wagon and has AFM enabled, but there is enough drone to shake the rear view mirror. Just wondering if there is anyone else in the same situation? i have heard of some people getting the exhaust tips extended a little to reduce the noise? or did i just get a dodgy exhaust? or maybe i am a little pedantic with the noise, i may be able to do a sound file or something to make things a little easier, i would just like others opinions, just to make sure im not going crazy here . When talking to the guys who fit the exhaust up, they seem to assure me it will "settle down after a while" im sure thats just the generic response though to get rid of me. Apologies for the long post.

 

[CSP]

Drone is almost always created through lack of adequate muffling. And drone is almost always eliminated by changing to better mufflers.

 

[unitdiplomacy]

yes, but guaranteeing "no drone" ...what do they base that on? is there a Decibel range ?

 

[TinSnips]

To be honest - I think the problem is the AFM. Does it drone only when AFM is active, or all the time? I think that KPM guarantee no drone for non-AFM cars only. It's not the decibel level that causes drone, it's the frequency. So when all 8 cylinders are firing, the exhaust should be emitting a frequency that doesn't drone - but by halving the cylinders (AFM active), you're altering the frequency - which seems to invariably cause drone. I don't know of anyone who has successfully put an aftermarket exhaust on a VE with AFM active and no drone. Changing the tips will only be of any benefit if the tips do not exit outside the vehicle. Some systems have the tips stopping just inside the rear bar, which allows sound to echo around under the car - but I don't believe this to be the case with KPM.

 

[jr689]

As for exhausts settling in, I too have heard this from where I got my system done at and also read it as well so I guess it's fact?

Yea flick up a sound clip, wouldn't mind hearing an AFM with a catback

 

[HUX 90]

A sound file will help, Mine has AFM too and a few exhaust shops told me that they'd install flexible tubing to reduce cabin noise, another exhaust shop said that getting 1 5/8" headers might also reduce drone from the AFM, but unfortunately they couldn't guarantee that there would be no drone when the AFM kicks in. You could just flip the gear leaver into manual mode because it doesn't drop to 4 cyl when manual shift is selected.

 

[Not_An_Abba_Fan]

The term "settling down" means that the glass packing loosens up a bit after a week or two and the note changes, also the exhaust will carbon up a bit too, this alters the note as well.

Most brand new exhausts sound different after a couple of weeks than they do when first installed.

 

[unitdiplomacy]

The Majority of the Droning is when AFM is active, talking with greg i think it was from KPM he said they only had trouble with one wagon that had AFM enabled and to stop the drone they had to disable it. I will have to get some pics / sound files up and show the set up, as im sure the exhaust tips finish a fair way before rear bar. If worse comes to worse ill just get the AFM disabled, i have heard of people getting better consumption with a cat back exhaust OTR intake and tune than AFM anyway..

 

[UFO]

Drone in your car can be attributed to a few different issues. As already pointed out above, AFM can definitely cause drone... but there's a distinct difference when you hear it 'activate'. Continuous drone is more than likely caused by poor rear muffler selection. This is especially important in wagons... because if Im not mistaken the rear mufflers in a wagon are slightly different to sedan/ute variants in regards to noise cancellation. The tell tale sign with mufflers designed specifically for the wagon (at least when dealing with Holden genuine parts) is whether the tips of the exhaust come out of the rear muffler as one pipe splitting into two (or in the case of sedans, two pipes coming directly out of the muffler). As the wagon body shape is more susceptible to drone, rear muffler choice is very important.

If as you say "you've got enough drone to shake your mirror", then no amount of changing other exhaust components will make as much difference as actually changing the rear muffler. As discussed previously in other threads (search), you can change the note and tone a little by installing aftermarket extractors etc, but in your case I'd be almost 100% sure that the cause of your excessive drone is rear muffler choice. You can also try to dynamat the rear section of the car (pretty easy because tyre well is readily accessible), but I reckon different mufflers will be your only option.

And I'd also definitely agree with exhausts settling in as suggested above. I've had a number of cars with new exhausts put on over the years, and in each of them the exhaust note changed a little over the first say 6 months. It got a little deeper (and in one case just a little louder). Up to you on whether you want to 'wait and see', but if it was me and my mirrors were shaking? I'd be pulling them off pronto! (Pretty easy job mind you... 2 bolts and they just slide straight off the rubber gromets). Ebay some different ones for cheap cheap and see how you go?

 

[unitdiplomacy]

A sound file will help, Mine has AFM too and a few exhaust shops told me that they'd install flexible tubing to reduce cabin noise, another exhaust shop said that getting 1 5/8" headers might also reduce drone from the AFM, but unfortunately they couldn't guarantee that there would be no drone when the AFM kicks in. You could just flip the gear leaver into manual mode because it doesn't drop to 4 cyl when manual shift is selected.

so is the Cabin noise really bad for you? oh and i have tried flipping to manual mode and changing to 6th gear, AFM still kicks in.