WhiteKnight16

I’m in the Dallas area and was hoping someone could recommend a shop to have my exhaust checked out? I have the UPD catless downpipes and Eurocharged Stage 2 Tune and everything is great except a rattle/sound wave sound that is completely different under full throttle. I don’t hear it when revving in Park or gradually driving and getting to the high range RPMs. I just hear this exhaust flap rattle or maybe it’s just the sound waves of engine/air flow through the OEM performance exhaust? It literally sounds like the valves are flapping really fast from all the increased airflow due to catless downpipes.

I was hoping someone has had both of these mods and heard this or at least a place they recommend in the Dallas, TX area to have it checked out? I went to Cedar Performance and they heard it too but said that the AMG engines all sound like this with these mods? They thought everything was healthy with the E63s. I’ve also confirmed no heat shields are touching and that there are no leaks.

OR maybe there is someone with a similar set up around the area that is willing to meet up and let me hear theirs?

I appreciate any help in advance!

apsuard

I know on the F10 M5 platform many guys had significant wastegate rattle with catless downpipes. I just gutted my OEM downpipes on both my F10 M5s so I didn’t have any rattle since OEM was double walled. My guess is that your catless downpipes are the culprit and it is wastegate rattle. I’m hoping I don’t have that when I install mine next weekend. That will drive me nuts.

Are your downpipes coated?

WhiteKnight16

The downpipes aren’t coated but do you think if it was a wastegate problem then I would hear it while reviving the car in park? It only happens while moving and under heavy/full throttle.

whoover

The wastegate limits maximum boost. You wouldn't expect it to open unless the engine is under load.

Ralcbah

Does it sounds like some rocks rolling around? If so, that is normal for your mods. Mine did/does the same.

apsuard

From catless downpipes? I don’t think I will like the sound of rocks rolling around

Ralcbah

Ah my bad man.

Mandarin

I know what you are talking about. A few days ago I went to dyno after catless downpipes and stage 2 tune has been installed. After dyno I rolled my windows down (which I never did before on any car) and open pano roof because as we all know after catless downpipes there is a lot of smell and was driving between 2 walls and I noticed something sounds like you said "rocks rolling around" I thought something got broken, but no errors or anything else and car is solid. I was wondering did I get mechanical problems or what...

But this never happens again since that day.

To be honest, I don't understand what sound you are talking about, probably you can take a video?

My car has AMG performance exhaust and catless downpipes now, only one thing I can see weird that sound at the 1st start is making a weird sound under the car like exhaust has a leak or so, but there is no leak at all.

I think this is happening because exhaust has valves and increased airflow is trying to go through them or so because if I'm going to open valves this sound is going away.

Also, catless downpipes will add a lot of metal jingle sounds at high RPMs to the exhaust's sound because there are no catalytic anymore which are removing airflow twists and making exhaust sound more "friendly".

MuffinFlavored

you have 2 F10 M5s?

apsuard

Sorry, I should have been more clear. I had a 2013 M5 then a 2015 M5. Very short time overlap

WhiteKnight16

So I ended up going to a performance exhaust shop here in Dallas and was told that the larger pipe diameters (Downpipes and midpipes) to the OEM performance exhaust (smaller pipes) causes a lot of back pressure? They said this was common on all AMG V8 twin turbos. Basically the pipes after the resonator is what they were talking about.

I know the sound of the car when it starts up and how raspy it is but this is under full load and the sound is completely different than all other types of driving I do in that car.

What do you guy's think? It's not like a rock clunking around but rather the exhaust valve flaps rattling super fast or like a rattlesnake sound when I put it under full load. I can try to get some videos right now and post for you all.

WhiteKnight16

Here are some videos. It's true that this is not portrayed well in the videos rather than in person but you can hear flapping/rattlesnake sound when you ignore all of the other normal sounds our AMGs make. I was hoping there was someone in Dallas or Houston with the same mods that would let us compare in order to determine if something with mine was off/not right.

Also, does the back pressure story i got from the custom exhaust shop sound plausible?

apsuard

I couldn’t even concentrate on the issue because it sounded so menacing. Can’t wait to get my catless downpipes installed next weekend!

Awesome car bro

WhiteKnight16

I've now talked to a few more shops and forum members and here is the answer I am getting:

"The added power and flow being put to the stock valve and cat back is creating too much pressure with the restrictive exhaust on there and that may be what is causing the fluttering of the valve. Without proper flow, the exhaust pressures may be beating the valve up a bit. The real solution is to open up the rest of the exhaust to relieve the pressure. You will probably see more power as well."

That being said, do you guys have any experience or suggestions on what I could do to fix this? I could talk to a custom exhaust shop and see how we can cut and weld some larger diameter pipes around the resonator and end of the exhaust but not sure how this would mess with the technology and electronics around this area?

Mandarin

I can't hear anything wrong or weird. Absolutely normal sound with the catless exhaust.

btw there are no resonators on AMG performance exhaust and if you are installing catless downpipes there are only mufflers left.

Stock diameter is 2.75" - downpipes are 3". I don't think it will cause any problems.

Only one thing I will concern about spool sound and airdrop sound. I assume you have aftermarket valves which make that loud sound.

P.S. I have a few videos of the sound of my car on my IG page ( AMG PE + catless downpipes) and you will see the same sound.

jkob5

Just watched the videos you posted and that's exactly how my C63s with catless downpipes sounded. It's just how these cars sound, much more "raspy" when catless.

blingperf

I have the exact same wastegate rattle since im catless.
so uncomfortable noise :-S

anyone has the solution ?

Grayblack

I had the wastegate rattle in my previous M5 after installing dp's. Unfortunately there wasn't a fix so I had to live with it.

raudiace4

This sounds great to me, and I can hear the slight rasp/flutter you're talking about.

I had this exact same sound after I installed catless donwpipes on my 2017 C63s, which was paired to an AWE track exhaust. I thought it was a noise coming from the DPs hitting against the heat shield under load causing that noise but could never pin it down. Perhaps it was the DPs touching the steering shaft under load? IDk, either way I got used to that noise and never had any problems mechanically.

I have a set of UPD coated catless DPs waiting for install for my 2019 E63s.

Ali_E55

check you catback valves, i saw a lot make rattle noise especially after installing catless DP.

you can go with Akraproik exhaust system if the stock mufflers valves are having issues, or you can go the cheaper way by removing them and coding the car to not show error