Exhaust drone

[HMS-S6]

Hi. On my URS6 I have 3" turbo back with one box at the rear. I love the sound of it and really don't want to just keep adding boxes to the system but the drone at 2,500 range is unbearable.

Has anyone has any experience with these;

https://www.google.co.uk/search?q=how+to+stop+exhaust+resonance&client=safari&hl=en-gb&prmd=svin&source=lnms&tbm=isch&sa=X&ved=0ahUKEwipuoL_n9_RAhVBGsAKHXUQBm4Q_AUICSgD&biw=375&bih=559#imgrc=kzgbRBe1UnnMsM%3A

(Sorry, I'm too I.T thick to load images )

I know JP's car has them underneath but it says 'don't ask' on it so I won't
I believe the have to be in a specific place to work correctly?

If anyone knows of an exhaust place to do this I'd greatly appreciate it.

[Error404]

Its called a Helmholtz resonator. They can work but there is a bit of maths involed in sizing them up correctly to deal with the right frequency.... not just a case of slapping one on!

[HMS-S6]

Do you or anyone on here know any exhaust place that would work it out and sort it?

[nip]

All I did was put a bigger box in before the back box cured it for me

[Rikki Kitto]

Avoid 2500rpm

[HMS-S6]

All I did was put a bigger box in before the back box cured it for me

Yeah, I was trying not to make it quieter on the outside

[HMS-S6]

Avoid 2500rpm

Lol, yeah I tried that and ended up with 6 points

[UrS4boy]

Hi. On my URS6 I have 3" turbo back with one box at the rear. I love the sound of it and really don't want to just keep adding boxes to the system but the drone at 2,500 range is unbearable.

This has come up many many times on my side of the pond. Classic result of people thinking they are smarter than the original designers.

The solution is you need a middle box.

If you can't afford a tried and true (and evolved to perfection) Stromung exhaust system for your C4 UrS, at least try to copy it.

http://www.stromungexhaust.com/92-955-s4-s6-ur-quattro.html

[A1QSHIP]

The two box 2Bennett 3" turbo back exhaust system I have fitted to my S6 does not drone.

Chris

[Morris400]

Middle muffler is key. I had the same issue. Bad drone at 2500 with no mufflers. Did a custom 3inch cat back with middle muffler and no rear. Much much better. No drone and really quiet.