[makkan00]

Guys
I am doing quad exhaust conversion on 520d.
I am with my installer.
He suggested that I should have two small boxes on each side to keep the back pressure, otherwise there may be negative impression on engine! He stated that it is relatively new car so no point of taking risk.
Just wondering what are pros and cons of having back boxes on diesels?
Thanks.

[CraigUK]

You might get a faster response on the f30 forum as there's a wider audience on there. Presumably the installer knows what he's talking about in which case you would be wise to follow his advice.

[makkan00]

Originally Posted by CraigUK

You might get a faster response on the f30 forum as there's a wider audience on there. Presumably the installer knows what he's talking about in which case you would be wise to follow his advice.

Thanks Craig.
Well I am going with his suggestion but wanted the normal consensus as well.

[CraigUK]

Get some photos up when it's all done. When are you getting your springs fitted?

[makkan00]

Originally Posted by CraigUK

Get some photos up when it's all done. When are you getting your springs fitted?

Springs will have to go after xmas mate.
Getting silly quotes to install springs and then alignment. £300!

So checking different places.

Will see if I can get decent photos at some point mate.

[ukbeemerboy]

Originally Posted by makkan00

Guys
I am doing quad exhaust conversion on 520d.
I am with my installer.
He suggested that I should have two small boxes on each side to keep the back pressure, otherwise there may be negative impression on engine! He stated that it is relatively new car so no point of taking risk.
Just wondering what are pros and cons of having back boxes on diesels?
Thanks.

I'd go with the same set up as the factory system comes with if I was you....

[makkan00]

Originally Posted by ukbeemerboy

I'd go with the same set up as the factory system comes with if I was you....

Thats what I did.
On 3 series forum (e9x), I was told that there is no point if getting boxes.
However I had to take decision on the spot and I went with 2 back boxes.
Happy with the results and now I can feel that I have an engine in my car.
It sound bit more throaty and rumbles on higher rpm.
No where near to petrol versions but still very good.

[valbmw]

This is correct decision, and congrats with the new exhaust! Let me add some thoughts about it.
Some people believe that being loud is equal to being powerful. And also there is a violent spirit of youth to show up, get noticed on the street, argue with cops about barely legal level of noise, make the friends impressed and attract chicks. Just visit any enthusiasts' garage and you will be told, there should be a catless DP and a straight 3.5" pipeline to make it sound like Mad Max.
But somehow none of the professional exhaust companies think that way, and the proper exhausts for street cars have mufflers even at the "race" editions. Adding dB to the car will never convert it to Daytona V8, but depending on piping design there is a high probability of a constant low frequency droning that will make you crazy.
There are many much more effective ways how to push your car, while the exhaust is made to combine flawless engine aspiration with comfortable street drive.

[The Beast]

I looked into getting a performance exhaust on mine and visited a guy who makes custom stainless steel exhausts for performance cars. He gave me a quote but warned me that upgrading the exhaust on a diesel is probably not going to give me the results I may be expecting.

He said whilst petrol cars will sound a lot nicer with a performance exhaust diesels tend to get more of a booming sound that can become irritating, he actually recommended that I leave the standard exhaust on the car!

[valbmw]

I believe the cheap factory thing is just ridiculous and doesn't fit BMW F10 at all. Even so called M Sport tips looked as stolen from my granny's Volkswagen. Got Supersprint quad instead, and now it looks complete and works perfectly.

[makkan00]

Originally Posted by valbmw

This is correct decision, and congrats with the new exhaust! Let me add some thoughts about it.
Some people believe that being loud is equal to being powerful. And also there is a violent spirit of youth to show up, get noticed on the street, argue with cops about barely legal level of noise, make the friends impressed and attract chicks. Just visit any enthusiasts' garage and you will be told, there should be a catless DP and a straight 3.5" pipeline to make it sound like Mad Max.
But somehow none of the professional exhaust companies think that way, and the proper exhausts for street cars have mufflers even at the "race" editions. Adding dB to the car will never convert it to Daytona V8, but depending on piping design there is a high probability of a constant low frequency droning that will make you crazy.
There are many much more effective ways how to push your car, while the exhaust is made to combine flawless engine aspiration with comfortable street drive.

Many thanks for your constructive comment.

[makkan00]

Originally Posted by The Beast

I looked into getting a performance exhaust on mine and visited a guy who makes custom stainless steel exhausts for performance cars. He gave me a quote but warned me that upgrading the exhaust on a diesel is probably not going to give me the results I may be expecting.

He said whilst petrol cars will sound a lot nicer with a performance exhaust diesels tend to get more of a booming sound that can become irritating, he actually recommended that I leave the standard exhaust on the car!

He is spot on. You struggle to get decent sound out of diesels, yet there are videos on youtube showing crazy diesel cars.

I did not want any crazy sound tbh and wanted decent quad exhaust to go with M5 body kit. Ended up having excellent results.

you can perhaps get the tips changes to thicker one and they will fill the diffuser better.