Sanch

I found this on Instagram, this gives a good indication to the coupe owners what the secondary cat delete sound like.

Sounds MUCH better than stock that's for sure!

Andyroo

The sound from the M177 really doesn't capture on video, does it? Still, sounds throatier and raspier. Standard M177 videos sounds like almost nothing at all!

Vic55

It sounds good mate but the arena where its filmed appears to give it more amplified sound too. Im trying to decide how bad I need this LOL.

See63esS

You need to do this and let me hear it so I can decide when mine comes in a few weeks

Guilty

What you need is something that starts with an A and ends with a č

AMG 17GT

Huh? Do I need that??

This mod is necessary. It's just more of a great thing.... about 8 decibels worth.

doryes

Hey mate have you lost any power after doing this? I removed resonator on my ML63 previously and lost a bit of power.

AMG 17GT

No power loss, just less engine brake maybe.

My car does not sound like that video. Mines octave lower and I don't have all those high ticks.

AMG 17GT

Short vid

trim.42CF3E37-E070-42C2-85BB-77275B9947F2.MOV

AlexZTuned

Sounds perfect! Any more sound clips or pics of the cat delete? I think this is the only exhaust mod needed... Sounds better than most cat-backs, only costs a couple hundred bucks, and a few hour labor.

Palpatine

Sounds amazing.

Let me get this straight... a couple hundred bucks at a muffler shop... no gas smell in your car... no loss in power?

Will the vehicle still pass smog?

My c63s sedan is leased... is this reversible?

Anyone know a good shop in L.A., or the San Fernando Valley, that has done this on a c63s?

Sanch

I know exactly what you mean, the shop seems enclosed and a lot of echo.

Well I will try get some good videos once I have it done!

skim7x

Correct me if I'm wrong, but looking at the diagram and pictures of the performances exhaust, if you simply go with a catless downpipe, you'll get rid of both primary and secondary cats, leaving the exhaust catless?

*and I realize by "simply", I mean dropping the transmission to swap out the entire downpipe.

Palpatine

Yah, but that's the whole point of this thread...

A significantly less intrusive, and significantly less expensive (like 90+% cheaper) alternative, that still provides satisfying results.

kuba.95

I definitely recommend the secondary cat delete. Got it on my car and it definitely made a difference in sound. It was also easy to do, and it was only about 200 Canadian if I remember correctly. From what I know it only takes an hour or so to do if the shop isn't busy.

Here are videos of my car.

Before the Secondary Cat Delete

After the secondary cat delete

Secondary Cat delete with software update

rbohgan

what software update is that?

I did my secondary cat delete on weekend. We just gutted the cat tho. far easier. sounds a lot nicer few pops in it now and much throatier. no loss in power.

Andyroo

Man, I've got my non-perf exhaust booked in to have custom rear straight pipes but now I'm worried this won't give me the same sound as gutting the secondary cats (but I'm anxious about cutting up the standard pipes rather than non-destructively swapping out the rear mufflers).

Will a rear muffler delete give a throatier sound like the secondary cat delete or just a deeper sound in people's experience?

skim7x

I'd imagine a rear muffler delete will be similar to the rear exhaust flaps since those basically bypass the mufflers, so you'd be getting closer to the performance exhaust sound. Still have time to change the order??

Really nice... the sound after the software update is exactly how I want my car to sound... some of the videos with cattless dp's are a little too much popping and clanging to me... almost sounds like the engine is broken or something haha...

What software update are you speaking of, btw? The exhaust update that has been mentioned before? I wonder if I ECU flashes (from eurocharged, renntech, etc) are incorporating the exhaust update as well -- or if it's even necessary for them to udpate.

Sanch

wow the last video almost sounds like a catless downpipe.

Andyroo

I think I'm going to stick to the muffler thing first because it's easily reversible, then assess if I want to swap for secondary cat delete or add secondary cat delete afterwards... here's hoping it sounds good! Should be a little louder than perf exhaust because there'll be no muffling at all, like the GT-S, which completely bypasses the rear muffler in loud mode (whereas the C63 goes through the muffler with some tiny slots in the pipe for sound reduction). Secondary cat does sound good though...

C63SEd1

What's the technical difference between gutting the secondary cat vs cutting it out? For gutting, do you still have to cut the distal end of the down pipe?

Thanks

AMG 17GT

Gutting these seems odd. I think your better served replacing with straight pipe so as to eliminate and back pressure created by the angles these cans have.

AMG 17GT

[QUOTE=Andyroo;7090957]Man, I've got my non-perf exhaust booked in to have custom rear straight pipes but now I'm worried this won't give me the same sound as gutting the secondary cats (but I'm anxious about cutting up the standard pipes rather than non-destructively swapping out the rear mufflers).

Will a rear muffler delete give a throatier sound like the secondary cat delete or just a deeper sound in people's experience?[/QU

They have a dozen engineers working to get that sound right on those mufflers.

The secondary cats I believe were put inline simply for cold startup emissions and noise there is no platinum in there, just some beehive looking material.

IMO your cutting out all that R&D that went into your cars sound.

AlexZTuned

[QUOTE=AMG 17GT;7092793]I agree with this. I recall seeing a video about the performance exhaust and they were so detailed in their R&D to get the sound right, even testing the exact number of holes drilled in one of the internal muffler pipes (I believe is was 9 holes).

The stock catback is pretty much perfect, I wouldn't mess with the rear boxes. If anything, delete the secondary cat and you have perfection through an OEM tuned exhaust.

Palpatine

Hey guys, I've been following this thread... And forgive my ignorance here, but I've got the performance exhaust on my sedan and just wanted to confirm this before I do it...

Is there a chance that by deleting the secondary cats that the car can lose power?