I never did a dyno. I also did them in increments - Brabus rear section, then added Supersprint midpipe, then added Rado catted downpipe.

Rear section is more free flowing that OEM, the mid pipe eliminates the resonators (i.e. even more free flowing), then the Rado with GESI 300 cell cats - made the entire rear exhaust much more free flowing than OEM.

You can hear the exhaust is more free flowing and the turbo sounds even come through.

When you add a tune on top of that, all of it together - absolutely you can feel the difference. Night and day.

I believe turbos benefit from low back pressure so my HP/TQ gains from the tune are most likely amplified by the free-flowing exhaust. But someone who knows more can comment.

I drove several thousand miles on the Rado downpipes with zero tune and no CEL. My tune also does not turn off the CEL/O2 sensors and still no CEL. So the GESI 300 cell cats are doing their job. I highly recommend them for any stock or tuned ECU.

 

`


Great information - great post -


Thank-You
D.B.


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I should add what is bolt-on and what is not.

1) Rado catted downpipe - bolt-on. Fits OEM midpipe/rear section (it's all one huge piece) and also bolt-on to supersprint mid-pipe (you need to purchase their adapters from Supersprint).
2) Supersprint midpipe - bolt-on to OEM Cats. You have to use the supersprint rear section or chop up the oem rear section since the OEM exhaust is one huge piece after the cats. You will also need reducers as the supersprint is 3.00" and oem is 2.75". ECS tuning is the only authorized dealer for supersprint in the USA. not on their website, you need to call directly to order. takes a while as it ships from italy.
3) brabus rear section - you need a reducer from 3.00" to 2.75" to connect the supersprint mid pipe. any exhaust shop can do it, but i ordered a custom piece online in stainless. i didn't even weld it on, just used high quality stainless steel clamps and tested for leaks. no issues. Now i can remove any section easily.

The brabus rear section is really the key in my opinion because it has a valved exhaust connected to the computer system (COMMAND?). You press and hold a button on the steering wheel and it opens or closes (up or down button) and it goes from tame to insane. Brabus actually calls it "coming home" mode and that's exactly what I use it for - when I'm in my neighborhood I close the valves so I'm quiet.

Open the exhaust, you have turbo whistles, burbles, etc. just insane.

 

 

 

There are certainly cheaper alternatives and possibly even better than Renntech but none I would trust more with a new car.

 

 

Thinking of replacing my resonator with this universal 3” Xpipe. What do you guys think as a simple mod before shelling out the cash for an exhaust?

 

Yes, I believe it is now on the OBD2 flasher.

 

 

 

1) Call Worldmotorsports and see if their downpipes pass CA emissions. https://www.world-motorsports.com/ra...downpipes.html They are in CA so they should know. If you just do OBDII check in CA for your year car, I would say it will because nothing is turned off and no error lights. Even with a tune, you can tell them to not turn off the O2 sensors (or whatever it is they do).

2) I don't know for sure if the Brabus fits the rear section of the GLS63, but I assume so. Worst case scenario you use the tips of the OEM exhaust. For the GL63, it works with the stock bumper:
https://gtfactory.ru/proekty/mercede...rabus-exhaust/

3) You can see a picture of the stock exhaust which should be similar/identical to the gls63. Any reasoning for the X-pipe? If you want something more quiet, I would understand that, as the exhaust frequencies would hit each other and cancel some noise out. With a twin turbo for hp, you want the least resistance flow straight through as possible (from my understanding, again, correct me if I'm wrong).

Case in point is I was going to get a x-pipe for my panamera turbo and someone did it before I did. It made the exhaust more quiet with no difference in feel. I left mine alone after that review.

4) Yes, removing resonators and replacing with straight pipe is the cheapest, fastest solution. Just be sure they use stainless steel and use someone who knows how to weld stainless steel and not use aluminum filler.

5) Capristo Axelback sounds cool - be sure to take pictures of the exhaust! really curious to how it all looks.

6) you want a warranty, go with Brabus Piggy back for 620hp. Check out OBDII tuning with OE Tuning. Jeremy has been around and knows what he is doing. You can ask for a burble tune too if you some extra sounds. You can also get several different maps, e.g. 91 octane, 93 octane, race octane, with burble, without burble, etc. https://www.pressertech.com/ is another good option where they tune within MB safety parameters. They also fix ECU's so they know what they are doing. Eurocharged also does OBDII tuning. Not sure if Renntech has OBDII yet or not.

 

Here is the info on the Renntech tuner. https://www.renntechmercedes.com/ind...6-gls63-detail

Nothing against OE but my SL has an OE tune and I still get CEL's from time to time. I could probably use a dyno tune due to all the mods. Seems to make good power though.

 

 

 

Can you please email a list of all CELs you are getting to sales@oetuning.com so we can address this for you. Our tunes should not cause a CEL if the correct tune for the modifications is installed.
Thanks

 

`


solomon@eurocharged.com

He will answer all your questions -

Incredible to work with -

By far the best price -

I did both the ECU and TCU tunes -

Outstanding with NO CEL's -

You should talk with him before you purchase

a tune from anyone - it's free to ask questions -


Thank-You
D.B.


.

 

it's running too rich. Seems to be a summertime issue. Mods:.Speedriven Intercoolers with BOV's mounted on the intercoolers, Speedriven down pioes, full exhaust, trunk tank, metal cell cats, and SL65 Black injectors. Rickers/Sean's old SL widebody 600.

 

 

 

Rear muffler delete will give it a more aggressive sound.

 

 

 

 

Before you get the expensive mufflers, try removing the stock ones. I think you will be pleasantly surprised.

Renntech sells an OBD2 lowering module for the GLS but it is expensive.

Is this the one on Amazon?