[Jim1985]

Is there such a thing as an aftermarket exhaust that doesnt whistle?

I'd like a little extra noise but I hate the whistle. Would a backbox delete give me a little extra noise? I'm probably going to take the lid off my airbox
(jokes)

[Aragorn30d]

I suspect the answer is simply no. the freer flowing silencers etc that give the increased noise, also allow the sound of the turbocharger to pass though more freely as well and you end up with the whistle.

You might find if you left the DPF/cat in place to muffle the turbo but had a free flowing system at the back, you might get a bit of extra exhaust noise without too much whistle, but i'm not really sure, and it seems a bit pointless paying for an aftermarket exhaust when theres a DPF and cat strangling the engine.

[Jim1985]

Good points well made!

[BionicYeti]

Has the exhaust been proven to be restrictive ?

I know the cat / dpf will, but will upping the bore size, straight piping etc give any actual gains ?

[jackstrath]

Originally Posted by BionicYeti

Has the exhaust been proven to be restrictive ?

I know the cat / dpf will, but will upping the bore size, straight piping etc give any actual gains ?

he is after engine noise , not power



as others said could put a cat in but i have a feeling it would still have the wistle

[Ess]

I've explored this quite a lot but I've been unable to find anything. The only unsolved mystery to me is Ungie's 320d which sounds damn good for a diesel and doesn't have much whistle. My understanding is he has just a back box delete and I've heard it in person and it really does sound good. Confused.

[Jim1985]

I'm tempted to unbolt my back box and see how it sounds....

Anyone have any ideas on db levels after a back box delete? Wouldn't want the same track day troubles I had with my Impreza.

[BionicYeti]

If you just want noise and no whistle then either removing or making the backbox smaller should be all that is required

Noise levels shouldn't be an issue unless straight piping in my experience. I managed to hit 102db in my old PD130 so had to get a small box fitted for track days, which brought it down to 97db

[Jim1985]

Fantastic! Thanks!

[Aragorn30d]

Is your DPF and Cat still fitted?

[Jim1985]

Yes sir. Completely standard.

[Mk1tony]

I deleted the back boxes on my 335d and it made very little difference to the noise to be honest. Now I have the dpf deleted it sounds good, but I do have the whistle you don't want. It's not terrible though

[Jim1985]

Do you notice it under driving? All the videos in YouTube are either revving with no load on the engine or rear bumper mounted gopros. Neither really illustrate what it's like from the drivers seat.

[Aragorn30d]

My brothers 320d has a decat and a 330d exhaust system.

It whistles quite noticeably from outside the car, but from inside its not really evident at all.

[harmeet]

DPF and back boxes have been removed on my 335d and whistles like mad when I'm driving around in the low rpm range. Sitting inside the car with the window closed you cant hear it.
On the plus side it sounds great when its getting thrashed

[Jim1985]

I might be able to put up with it...

[jackstrath]

Yeh from inside the car sounds very little difference tbh , outside of windows down in town (with buildings to echo off) you can hear the turbo whistle , car sounds mean from the outside on load tho, once the wastegate opens it has a fair roar to it , just from inside the car windows up its not loud at all

[Jim1985]

I'll have a listen when I get home - no sound at work!
If theres not too much difference inside the car I might not bother doing any exhaust work unless its for power...