[Sprinterman]

I’ve a 320d f31 (uk) remapped. It has a single exhaust which produces not a lot of sound. Im thinking of having the back box removed and the dual pipes with a rear diffuser. Question is, will it produce a better exhaust note, I’ve seen some videos where the 320ds which have had this done sound pretty good. The DPF has to stay on due to emissions tests. Any ideas anyone?

[Watsey]

Short, simple, answer to the question "will it produce a better exhaust note ?" = no.

Slightly longer answer = it's a 4-cylinder, diesel, with a DPF, and doesn't rev very high. Replacing the existing back box with an OEM back box from, say, a 440i, really isn't going to do much.

There are passive aftermarket systems which can, very subtly, change the exhaust note but it's really not worth the hassle or the ££.

There are also replacement exhaust systems, mid section + back box, which have an active sound generator but they are (comparatively) pretty expensive.

320ds which have a louder exhaust will almost certainly have had the DPF removed or gutted, and that's a mandatory MOT fail. Plus removing the DPF, especially if the car then smokes, just screams 'tw@t'.

Why not spend the money on something that will make a difference ? Better tyres, brake pads, suspension, etc.

[Sprinterman]

Thanks for the detailed reply, was just looking to make the car sound as good as it looks, it’s been remapped to 240bhp, it’s more then enough without losing your licence in the UK with speed cameras everywhere. I guess aesthetically the dual pipes with the rear twin exit diffuser would look great, but can’t justify £700 if it doesn’t change the exhaust note. I’ve seen those active sound exhausts and they do sound really good, but your looking at at least £1200 without fitting and labour costs. I’ve got the car exactly how I want it, done a lot of work on it myself, some claim they’ve created this louder exhaust by keeping the DPF and removing the silencer, rear box, and just straight pipes, which would pass the emissions test. So I’m a little confused about that, I’ll sit on it for a bit and decide what to do

[Watsey]

Originally Posted by Sprinterman

Thanks for the detailed reply, was just looking to make the car sound as good as it looks, it’s been remapped to 240bhp, it’s more then enough without losing your licence in the UK with speed cameras everywhere. I guess aesthetically the dual pipes with the rear twin exit diffuser would look great, but can’t justify £700 if it doesn’t change the exhaust note. I’ve seen those active sound exhausts and they do sound really good, but your looking at at least £1200 without fitting and labour costs. I’ve got the car exactly how I want it, done a lot of work on it myself, some claim they’ve created this louder exhaust by keeping the DPF and removing the silencer, rear box, and just straight pipes, which would pass the emissions test. So I’m a little confused about that, I’ll sit on it for a bit and decide what to do

You might hear some change in the exhaust note if the back box was removed, but from the conversations I've had with people (including those that provide custom exhausts, i.e. back box removal) it's very subtle.

I went through a phase of considering it for my 30d but it just didn't seem worth it. The DPF muffles a lot of the cylinder noise, but I won't be removing mine a) because it's there to an important job, and, b) you can hear a lot of turbo whistle if the DPF is removed and that's just not my thing.

By all means do it for the looks, but keep your expectations realistic in terms of the sound.

[Sprinterman]

I hear you mate, removing the DPF isn’t right, like you said it will pump out black dirty fumes and fail the mot. These videos showing a big increase in sound, they must of removed the DPF, as the consensus is that removal of the backbox and a Catback won’t make much of a difference in sound to justify the cost. I’m
Tempted by the active sound exhaust as I’ve no intention of selling the car after all the blood sweat and tears restoring it. I’m
Guessing a Downpipe means also removing the DPF? just looking at the options left

[_F30_UK_]

I've had this done on my 330d. On Normal mode, there isn't much difference. But there is definitely a sound improvement on Sport mode. It sounds deeper and more "powerful". It is still a diesel though, so don't expect too much. I'd recommend it.

[Watsey]

Originally Posted by _F30_UK_

I've had this done on my 330d. On Normal mode, there isn't much difference. But there is definitely a sound improvement on Sport mode. It sounds deeper and more "powerful". It is still a diesel though, so don't expect too much. I'd recommend it.

Different back box, or back box delete ?

[TurboWeasel]

The only BMW diesel worth bothering with for exhaust sound is the E38 740d V8. That does actually sound half decent with a silencer delete.

The 4 pots I just wouldn't bother with personally. No 4 pot sounds good imo, petrol or diesel. To my ears they just sound as thrashy, rough and unbalanced as they mechanically are. Then again, I'm more interested in acceleration than noise unless it's a V10 or something equally charismatic.

The 6 pot doesn't sound too bad when hard on the gas from 2500rpm but even then it's more gruff than tuneful.

Originally Posted by Watsey

Why not spend the money on something that will make a difference ? Better tyres, brake pads, suspension, etc.

100%. The stock chassis setup is the only weak link on the F3x platform imo, and limited run flat tyre choices.

[Cully]

done a backbox delete on my f31 335D and it sounds great on boost, deeper tone when the exhaust is hot, it has a nice rumble on idle and does sound cheap or tacky.

back box & secondary DPF (spill cat) removed

[OMG73]

Originally Posted by Sprinterman

Thanks for the detailed reply, was just looking to make the car sound as good as it looks, it’s been remapped to 240bhp, it’s more then enough without losing your licence in the UK with speed cameras everywhere. I guess aesthetically the dual pipes with the rear twin exit diffuser would look great, but can’t justify £700 if it doesn’t change the exhaust note. I’ve seen those active sound exhausts and they do sound really good, but your looking at at least £1200 without fitting and labour costs. I’ve got the car exactly how I want it, done a lot of work on it myself, some claim they’ve created this louder exhaust by keeping the DPF and removing the silencer, rear box, and just straight pipes, which would pass the emissions test. So I’m a little confused about that, I’ll sit on it for a bit and decide what to do

I got mine from pipe dynamics, approx £350 I think. For that money the aesthetic improvement alone is worth it.

Mine is a remapped 30d and there is a subtle exhaust note change as stated.

For the money above highly recommend it.