Brabus SL

Hi Guys, I have asked this question previously but unfortunatley I did not get any replies, so I am asking for help again with this question.

I have decided to seek more power from my Brabus Tuned 2003 SL55 AMG. my first area for upgrade was to replace the stock headers with Kleemann headers, my complete exhaust system is Brabus with 2 pairs of metalic Cats, checking what type of design the exhaust system is, I hoticed that there are 2 link pipes, one before the secondary cats and one link after the secondry cats but before the resonator, not sure if these are classed as "H" pipe desigh (view video here) and here

I tried to get an answer prior to installing my Kleemann headers but was not able to get an answer, so I contacted Kleemann in Denmark and asked them the question, they said that the most restrictive cats were the primary ones, so to get the most HP gains these were the best ones to remove, so this is what I had done. but it seems that most people are keeping their primary cats and deleting the secondary ones, some replacing secondary ones with ann "X" pipe, but I have read that the "X" pipe needs to be installed as close to the front as possible!

Then we have the concerns about the need for "back pressure" to maintain low end torque and how you loose your bottom end torque if you have straight through pipes with no "H" or "X" pipes! (is this correct?)

1, Should I have kept my primary cats and deleted my secondary ones?

2, Are my link pipes on my Brabus exhaust design considered to he "H" pipe design?

Thanks in advance.

cal1

I think you did the exact right thing. Removing the primary cats definitely removes the most restriction. Replacing with hi-flow or race cats is the way to go or even better, long tube headers which eliminates the primary cats completely.

I think the reason why you see so many people removing the secondary cats only is because of ease of the mod and cost. This is why I did it. Removing the primary cats is more expensive and can create 02 issues or will create 02 issues if not done right.

As far as the back pressure issue, this seems to still be controversial. I have heard that our blown motors don't like back pressure so reducing it is always good. I would think removing your secondaries as well would be a good thing. You might ask the guys on the E55 forum or maybe someone more knowledgeable than I will chime in. If you are interested, I would be happy to share with you the secondary cat delete using a piece of 3 inch stainless "U" bend.

Finally, your link pipes definitely look to be "H" pipe design.

I bet your car sounds sweet.

Brabus SL

Thank you very much for your informative post Cal1 most appreciated. This back pressure issue is a real mistery, some say blower cars need back pressure and some say they dont, most readings say our s/c cars need back pressue to produce low end torque and some say X pipe to replace secondary cats!!! Where does it end. Lol

Thanks again for your advice

mbegdouri

I have an 03 CL55 & i want to make some changes to the exhaust. What sort of sound would I get from removing the secondary cats and resonators ONLY ? Would I see power gains from doing that? Any suggestions? should i set up an x-pipe instead of the secondary cats or not. I will leave the primary cats to avoid any problems with the O2 sensors.
thanks

Thomas668

any picture of the installed "U" BEND

Thomas668

just try to remove the resonators first

and you will have a big surprise

there are lot of video clip on youtube with the resonators off

try to listen to it and design what you going to do

cal1

I don't have any pictures so you got one of my fabulous drawings instead. My 4 year old granddaughter could do better.

The "U" bend is cut off center as shown. The secondaries (158 on the diagram) are cut out. The two pieces of "U" bend are welded in as shown. Once the secondaries are cut out, it becomes pretty obvious how the "U" bend needs to be cut. Hope this helps. It is a nice mod. You get more sound under throttle and pretty much stock sound at idle. Minor HP gains as well.

Thomas668

Thanks

Tamimomary

Now doing this will it make the car illigal? Because you are messing with the cats.

cal1

I think it depends on what state you live in and then your only issue is passing smog. What state do you live in?

As I understand it, the secondary cat was included by MB in preparation for an upcoming EU emissions requirement that far exceeds anything we have in the US. I have had no issues passing smog in WI and of course no issues when I lived in Indiana, because they have no smog testing on cars.

Removing the cat does not cause any codes nor do I think it effects the emissions levels significantly. I believe some states like CA are supposed to visually inspect the exhaust system for changes. I cannot imagine an inspector would put the car on a lift and remove the under panel during his inspection.

Tamimomary

I live in California. And the smog guy that I go to doesn't have a jack.

cal1

I honestly think you will be fine.

Here is a suggestion. The E55/E63 guys are the biggest group of modders on the board. I know a number of them live in CA and have headers and other exhaust mods. You might pop over to their forum and ask them. We share the same motor but our exhaust system is a bit different.

Tamimomary

Thanks for the tips!

Ajai Thomas

I just took off my resonators today. I went to the local Midas in Mineola, Long Island. The head exhaust guy is a magican. They also recommended i take off the secondary cats and that they can do it for me. They told me to do it in stages so i can see i it feels and sounds after each so i don't bite off more than i can chew in one shot. Great shop for exhaust work. Just no headers. The manager is Tat Kong and it's Midas - 202 Herricks Road, Mineola. Very knowledgeable guys.
Cheers
J