[Jimmy-F46 M-sport]

Hi all,

Just joined the forum yesterday so hello from ayrshire 👍 I've recently bought a e91 320d msport (m47- 163bhp) with the droopy exhaust. My original plan was to get the local custom exhaust place I use to weld on a new tail pipe (twin 4") but after seeing some tourings with 335i style exhausts ( single 4" either side of car) Im thinking of going for this. What I want to know is, are diesels really that quiet as I've heard some people saying you can get away with no back boxes😳 is this true? All info will be gratefully received 😉

[Reece]

Welcome, i have a n47 320d with the 335 exhaust conversion with no back boxes and its not at all loud, get a tiny bit of jet noise on full throttle but thats it

[Brian mc21]

No need for a back box. Started mine after cutting the back box off for conversion and little or no difference in sound.

[Ess]

I don't understand this, because I've had other people say to me the opposite - i.e. just remove the back boxes and you will get a much louder, awesome sound.

Ungie 's car for example sounds immense for a diesel, and if I'm not mistaken he's just removed the back boxes?

[Phil99z]

With diesels revving so low anyway you won't notice anything minus the backbox. I've been in some diesels without the backbox and it didn't sound any louder to me.

Cupraraj has a 335 style conversion on his 330d and I'm sure he can vouch for the difference (if any) in noise.

I've got the 335 conversion with twin 4" pipes on my E91 and I think it looks the business but since mine is a petrol I had to have a new backbox.

[Brian mc21]

Can guarantee this pal. On my 320d I fitted a bcs back box and hasn't it tight enough and it popped off on my way to work. Stopped and got it off and into the boot and travelled into work with no silencer and no noticeable extra noise. Just had the 330 done dual exit with no back box and again no noticeable extra sound.

[dy63]

you wont notice any difference in sound back box there or not unless you pay real close attention. cabin noise is the same unless the exhaust place tweaks it to make it louder by adding some screamer thing in there which some do

ive done this on 2 of my 320d's and 3 of my 330d's lol

you dont really need a back box anyway tbf. i never had one and fuel was really the same without it.

[Jimmy-F46 M-sport]

Cheers for the replys guys 👍 that should keep the cost of the conversion down if no back boxes are needed😉 there is a guy near me with a e60 5 series diesel with a full m5 look conversion with quad pipes and it sounds Absolutly awesome

[dest]

I've just changed the clutch on my gf's Mini Cooper D and started it to check for leaks with no exhaust fitted at all and it was barely any louder than normal.

[Ess]

I asked the same question a little while ago because I wanted a better louder sound and most of the replies suggested that removing them would make a difference, have a look at the thread:
http://www.e90post.com/forums/showthread.php?t=1085405

Now I'm just confused....

[dest]

The turbo reduces a lot of noise on a diesel but I wouldn't remove that lol