I.T. Guy

Alright.
Most of the AWD downpipes are actually midpipes. OK. Yes. One can also see where they have to step down to connect to the smaller bridgepipes. Ok.
There are some real downpipes (bridgepipes replaced too) that are full size all the way to the turbo, and for AWD require different engine mounts, dropping the engine, etc.

My question is has anyone actually done a before and after dyno/track/anything Cat vs Catless? Or are pepole just ripping them out, creating smells and noise, with no extra power?

This thread has the fastest E63 cars in the world, some have stock cats. Look at the picture of the excel sheet that's posted - there’s a “Cat Deleted” column:
https://mbworld.org/forums/w212-amg/...-part-two.html

And this thread here @PeterUbers is making 730/780 thru stock cats:
https://mbworld.org/forums/w212-amg/...internals.html

Sooooooo
Should I bother doing anything about my stock downpipes if I'm keeping the stock turbos?!

I've been looking at midpipes - MBH and Kooks and Red Star and it hit me - research first. So I read through all these threads (and more!) and no one ever seems to have done a test before/after either dyno or track:
https://mbworld.org/forums/w212-amg/...-opitions.html
https://mbworld.org/forums/w212-amg/...downpipes.html
https://mbworld.org/forums/w212-amg/...e-install.html
https://mbworld.org/forums/w212-amg/...selection.html

Anyone have any real proof after all these years?

MBH motorsports

Our Downpipes are currently on sale. We make out downpipes in the USA from USA made 16 gauge RathGibson (the best stainless steel you can get) 304 stainless steel. No one else is doing that that we know of for Mercedes. We use a CNC mandrel tube bender to reduce welded joints. Unlike some others ZERO of our money helps support the atrocities being carried out in Ukraine.

Rehabguy

I dunno if you came across this post.
Best Return on Investment Mods List
My heart wants Downpipes... logic dictates TCU + ECU Tunes.

C2 Turbo

I have Weistec catless DP and I tell you, best mod ever. Car sounds awesome and I have never smelled any fumes inside or the outside of the car. Love it

I.T. Guy

I've been doing more digging. It looks like it maybe 30-40ish HP gain going cat-less mid-pipes.

There is a lot of great info in this older thread:
https://mbworld.org/forums/w212-amg/...turbo-car.html

Specifically
https://mbworld.org/forums/w212-amg/...ml#post6786153

And
https://mbworld.org/forums/w212-amg/...ml#post6788340

I decided to buy some used mid pipes to save money, since I'm still not entirely convinced. It'll be easier to get my money back from a used set if I decide to just put the stock ones back on.

I.T. Guy

I have all this stuff here ready to test on my next track day:
BB Intake
Lighter Battery
TCU Tune

After I see what that all does "stock" I plan to go in for an ECU dyno tune. Because dyno time is pricey I'm trying to decide if I throw catless DP's on before the tune or not. If I don't have to I'm perfectly happy with the stock sounds and smells. I just don't want to leave too much HP on the table, that is what would sway me to do it, the HP. 20-30? Meh. 40-60? Ok you have my interest.