Yuriy_Moscow

After a very long and extensive research on the exhaust systems for our C43/C450 AMG, I decided to install the AMG Performance Exhaust system U78 (hereinafter PE).
But before describing the process of searching, buying and installing, I would like to tell and show why I chose this particular solution for the exhaust system. First, a little about the system itself.

As we know from the factory, there are two exhaust system options on the C43 / 450.

1.U21 AMG Sport Exhaust - standard sports exhaust system
2.U78 AMG Performance Exhaust - comes as an option, improved exhaust system, popularly called PE.

For clarity, here are both exhaust systems laid side by side, without mufflers.
U21 and U78 side by side

U21 on the top, U78 (PE) on the bottom.

The difference is that PE is more straight-through - it has an H pipe and valves on the mufflers, activated from a button in the car. The valves are not that simple ... They are connected to the car through the module (controller), which regulates the % of its opening. In "comfort" mode, it is 30% open. In sport + mode, it opens slightly, depending on the speed. For example, sport + at 5000 rpm, it is 100% open. Very difficult, but that's how it is programmed by AMG engineers. You will see some more info about it down below.

I am attaching a couple of videos that were filmed from the same place and at the same time to compare U21 vs U78.

C43 AMG U21 AMG Sport Exhaust

C450 U78 AMG Performance Exhaust (retrofit)

Of course, the test is far from ideal, since the C450 is louder from the factory, and it has 1 less resonator, but still... The difference is obvious. The exhaust is louder. Delicious shots. A lot of content has already accumulated, since I personally met with 2 owners who put PE instead of the usual and chatted with many people. So I decided to accumulate all information in 1 thread for you guys!

So why am I doing this for? 99% of C43 cars in my country are supplied WITHOUT the Performance Exhaust option. The option is not cheap and dealers usually do not add it in the configurator, as it does not greatly affect the sale. But how does it affect the sound ... Accordingly, 99% of owners receive a "muffled" version of the exhaust system. Moreover, as I found out recently, on the cars of 2018+ (facelift), 2 resonators were installed! Compared to only 1 on 450 and pre-facelift C43. And all because of the new requirements and regulations on exhaust emissions and noise ... The sound of gear changes in SPORT + is quite good, but not so loud and the shots on the throttle (revs) are very much drowned out. They are practically absent. Someone may be satisfied with this, but not all.

Before buying, I understood that the configurator on MB website had this option and had already read quite a lot on the MBworld forum and in the FB group of C43 owners - that PE is a mandatory option when buying this car. Many wrote that without this option, they do not recommend buying a C43 at all. It seemed to me that these are strange people and in any case, the car should sound great. I was wrong.

It all started just a couple of months after the purchase. At first, I was overwhelmed with positive emotions from the car. I liked the dynamics, studied the behaviour of the gear box for some time, and got used to the car in general. It was winter and I didn't pay much attention to the exhaust system. After a few months, I began to understand that the sound of the exhaust was not enough for me. It seemed to me that it was muted and I began to study the reasons and look for an alternative ...

I started chatting with the owners of the C43s / 450s. I am attaching several conversations of people who have already gone through the stage of "modification" of the current exhaust system and their comments. All of them understand the essence of PE and recommend this option for an installation.

1. Michel from Brazil
He tried several options for improving the existing exhaust system, including options with electronic valves. As a result, he decided to roll back and return everything back to stock. In his country, the C43s are not supplied with the PE option at all. He was afraid to buy and bring PE from abroad.


FB chat with Michael


2. Milton from the Netherlands
He decided to make a copy of Performance Exhaust, but custom-made in his workshop. Moved away from the Y pipe and put the H pipe with electronic valves at the end, as it was done in the original PE. He argued that the original PE exhaust is an expensive thing to buy. This option was also offered to me in one of my local garages, but based on the comments and reviews this option is not very reliable and highly depends on the skills of mechanics & materials used.


FB chat with Milton


his setup


3. David from Australia
After a long search for sound, he also decided to make a choice in favour of installing a full PE system. Many refer to his article, where he talks in detail about the algorithms for the operation of the PE control unit and shows the installation process. The full thread can be found here.
He makes interesting observations (all credits to “Spaeggettio” from this forum)

• when the car is shut off, the valves are always open
• when the car starts, the valves close automatically after 3 seconds
• in mode "C" with the active button PE, the valves are open by 30%
• in the "Sport +" mode, with the PE button active, the valves open to 100% after 4000 rpm. At a different number of rpm, the % of opening varies.
• there is a controller which regulates this process.
• he contacted several tuning studios in Sydney, they told him that visually on the maps they did not see the difference in the firmware of the car with and without the PE option.

the module that controls the operating mode of the valves.

Video of his first start after installing PE:

More videos can be found here

P.S. a lot of discussions about Performance exhaust U78 vs sport exhaust U21 are happening in Russia. People are also concerned about the sound of non-PE. We have local forum called Drive2 where people post about their cars. Most of my communication happened there. I will make a translation of my dialogues with the owners.


4. Evgeny from Moscow
One of the first to see his post on the local forum in Russia about retrofitting PE. I immediately wrote to him in a personal message with questions. Here is his answer.


chat on the local forum with Evgeny

I decided to ask him to meet in person in order to listen to the sound live for the first time and talk to the person who had already done the PE installation.
This was the first time I heard PE in reality. I really liked the sound. Deeper and more bassy. Not smoothed, like mine. Shoots great, both on the gearbox switching and on the gas release. We recorded a couple of comparison videos. It turned out not perfect, as there was ice in the parking lot and it was not always possible to “catch the road”. But the difference is obvious.

AMG normal sport exhaust U21

AMG Performance Exhaust U78


5. Alexey from St. Petersburg
Met him also on the drive2 forum. I saw a post that he made a retrofit of Performance Exhaust instead of a stock one. It was not possible to meet with him personally, even though I was in St. Petersburg for a while, but we talked quite closely on the forum, where he told in more detail why he chose this option and, most importantly, who helped him find the exhaust. I believe he bought it in Polish auction called Allegro and transferred from Belarus to Russia. Such a long way. Here is his comment, which once again inclined me to this option.


chat on local forum with Alexey

Video of his PE exhaust installed


6. Alexey gave a contact to Anton, who helped him find Performance Exhaust. I did not hesitate and wrote to him directly that I also want PE and asked for help in the search. At the same time - asking a bunch of questions and making sure that he also unambiguously recommends putting this particular exhaust. And I was lucky. He said that there is a guy in Moscow who is going to sell his car and he can sell his PE exhaust to me separately.

These are just a few of the people I talked to. As you already understood, everyone recommends this particular option with the installation or retrofit Performance Exhaust U78 for our C43. I thought about it for some time, but in the end I decided to buy the exhaust for 1350$ from this person. Then I realised that this choice was the right one, since finding PE in my country is a rarity. The guys dragged their exhausts from Poland, Belarus and other countries. Almost with closed eyes and with advanced payment…Feeling lucky here.


This is my PE track. Such a beauty. Costed me 1350$.

I decided to install it at one of the local garages who deals with exhaust, since many people recommended the place and the mechanic who works there. The process is not very difficult, as the whole exhaust had to get back to its "bolt-on" place. Same as the original.

This is what the stock exhaust looks like. 2 resonators and Y pipe. Soon to be removed.


The guys are working hard. They are removing the existing exhaust.


2 exhausts without mufflers nearby. On top is PE in which -1 resonator and H pipe (more direct flow).

Video of the bottom of my car without exhaust:

Video of the installed PE:

The whole process took about 2.5 hours. The guys did their job perfectly well. Disassembled and assembled quickly. Everything fell perfectly into its native places and bolts. The only thing was to bend a part of the thermal insulation on one side, since the stock muffler is slightly smaller in size. The previous owner of the PE warned me for this moment.
ONE IMPORTANT MOMENT: if you decide to buy PE, make sure it has BRACKETS FROM PE OPTIONED CAR since stock ones don’t fit.

The valves are now 100% always open. I plan to change them and put them on the remote control to control the position. I have already purchased the valves. Here they are:

Electronic valves. Costs around 100$ for the set.

Well, in the end, a video recording of the first start with a new exhaust and a couple of accelerations from a standstill.
Listen only with headphones. Otherwise, you won’t hear much...

First cold start:

Vimeo

Acceleration from the back side:

Acceleration from the side:

P.S. As we all understand, it is very difficult to record the sound of the exhaust on the microphone of the phone, so I am posting what I have. According to my feelings, the sound was not even 50% transmitted. In fact, it is thunder and lightning. I plan to make a separate post and get a little more advanced with sound recording in a more professional way, but this will be another thread, if you want to

I am very happy that I bought and installed PE. It's not for nothing that AMG's R&D departments are investing millions of dollars in the development of exhaust systems. The sound is very "noble". There is deep bass at idle, crazy shots on upshifts. Shots on lower rpms are also present, especially on a heated exhaust, but they are not as high as on the C450s with PE. As I understand it, apparently it depends on the firmware. Compared to the stock exhaust, this "suffocation" is gone. The exhaust is now exactly what it should be on an AMG car. Many thanks to the guys from the local forums and FB group for putting me to the “right track”.

I hope this article will be useful for C43 / C450 owners. Of course, I understand that the taste of the exhaust sound can be different. To each his own. But as for me, this is the most ideal solution for our cars.

Best Regards,
Yuriy

waisoserious

Somebody 2 or 3 years ago also did this same retrofit. From what I remember the coding was a big pain in the butt. But Im glad you got it to work.

What are those cylindrical attachments on the frontpipes (portion that attaches to the cats, behind the resonator)? They seem to be present on both the U21 and U78

Also does the U78 have valves on both mufflers? I only see 1 in those pics.

Does the U21 have any valves on it at all?

Yuriy_Moscow

In cars with PE option installed by mercedes, centre console button connects to a module which is connected to the "head" of the car in order to read RPMs and other info (picture attached). This module connects to the valves via pins on the valves. It controls % of opening, depending on the mode of driving. In my case, I don't have neither button nor module. Valves are 100% always open. So I haven't coded anything.


Module

I am not quite sure what they do Good question.

Yeah, both of them have valves.


U21 (amg sport exahust) doesn't have valves at all.

AMGSOME

Awesome job @Yuriy_Moscow !
I was thinking of doing the same last year to mine can, and even found PE for sale in my country but wasn't sure about the ECU and valve - didn't really want to retrofit it and mess with the main loom. Can you link to this valve kit you've posted? How is it being powered?

I need to look for PE once again.. I was already set to buy an aftermarket one, but all of them sound pretty average

How's riding with flaps open all the time? Isn't too loud when just cruising around i.e. motorway?

Yuriy_Moscow

No need to mess up with ECU, it is just a simple replacement.
I bought a set of these valves from Aliexpress: https://aliexpress.com/item/10050012...264d33ed6sMzWV. It can be powered from power source, which is located in the trunk. There is even a whole from the bottom of the car to the trunk, so no need to drill or cut anything. Should be an easy connect. However, in order to install them, valves from PE have to be cut off and replaced with new ones by wielding them in. This part is a little risky since it will really depend on the welder.

Currently, I have not big problems with riding with open valves all the time. If the music is off, and there is no traffic, there is a little drone on 1500-2000 RPM. But no vibrations and it is not that disturbing. On higher speed and on 5+ gears, it is almost not noticeable. I want to install the valves only for low RPM. For example, when I am in traffic and want to relax from the exhaust sound

Recently, I have found a better solution. Without cutting PE valves.
The company is called schawe-shop.de.
They have 2 options:
1. The SCHAWE flap control system enables the retrofitted flap exhaust system to be controlled manually via the Mercedes-Benz switch block in the front centre console similar to the C43 with AMG performance exhaust system (Code U78). The driver can change the sound image at the touch of a button via adjustable exhaust flaps and set the vehicle in the right acoustic scene. A maximum sound experience, from comfortable to highly emotional, is thus made possible.


This is how the set looks.

This is going to look like OEM.
2. Manual flap control enables you to open/close the actuators on the rear silencer, e.g. on the C43 with AMG performance exhaust system (Code U78), yourself at any time. The operation is carried out via a high-quality handheld transmitter by radio and the following three start profiles can be saved.

Retrofitted valves will be operating from the remote.

I really like these 2 options. They are quite expensive, but look more like OEM.

AMGSOME

Ugh, didn't expect to weld and cut out the flaps...

I've seen that SCHAWE solution in one of your replies to PE exhaust on Facebook. I was a bit shocked with the price for it... It's actually cost of an second hand PE exhaust itself But definitely the best solution

Yuriy_Moscow

It is the only way. I have spoken to a person who already did that. He told me it is not a big deal for a professional welder. But yeah, it is always better to keep the original valves in place and be able to control them.

The price seems crazy, I agree. But it is the only option available in the market. I have researched a lot . I will contact them and try to get it lowered, but I don't think they will go too much down...

stockbmw

How much labor did it cost you for 2.5 hrs in Russia? In Canada, average shop would charge around CA$250 or U$190.
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Yuriy_Moscow

The whole replacement process costed me 70$. Labor cost is much cheaper in Russia.

ACC2

Has anyone heard of someone fitting a GLE53 PE exhaust on a GLS450? The two trucks share the same chassis and I suspect they would fit up fine or close enough to modify. The issues with valves and valve control would be much the same with the C450/C43. The GLS450 has valves, but no button to control them.

I’m just desperate to find a relatively easy and not prohibitively expensive way to add some excitement to the GLS. Any help is greatly appreciated!