2021 C63S Cat delete & Resonator Delete
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Junior Member
Joined: Oct 2021
Posts: 23
Likes: 2
2021 C 63 S
2021 C63S Cat delete & Resonator Delete
Ok so I don't know **** about moding a car prior to this. At around less than 1k miles, I went in a muffler shop to get a cat delete but all he could do for me was to "knock out the honeycombs and it would be the equivalent of deleting them". I was in a hurry but it seems like he wasn't sure which ones were the 2nd cats. Either way I paid the $200 and left unsatisfied. and now after 5600 miles, my car is still not loud with a Renntech EVM and mostly driven in S+, although recently I did some road trips and drove in Comfort most of the time.
Does anyone with a 21 model wanna chime in if they were able to get the cats deleted? if this model in particular has a weird setup, is the next step to delete the resonator and replace with a straight pipe? Please help!
Does anyone with a 21 model wanna chime in if they were able to get the cats deleted? if this model in particular has a weird setup, is the next step to delete the resonator and replace with a straight pipe? Please help!
Newbie
Joined: Feb 2022
Posts: 5
Likes: 2
From: Los Angeles
2021 C63 Coupe
I have a 2021 C63 Coupe and just had Redstar downpipes installed. It replaced both my primary cats along with the secondary ones. There is not much drone driving at highway speeds and I wouldn't want the car to be any louder than it is now. Worth the money and the time for the install. At first I was skeptical that it would be too loud or would consist of too much burble but it sounds amazing.
Thread Starter
Junior Member
Joined: Oct 2021
Posts: 23
Likes: 2
2021 C 63 S
I have a 2021 C63 Coupe and just had Redstar downpipes installed. It replaced both my primary cats along with the secondary ones. There is not much drone driving at highway speeds and I wouldn't want the car to be any louder than it is now. Worth the money and the time for the install. At first I was skeptical that it would be too loud or would consist of too much burble but it sounds amazing.
Member
Joined: Apr 2017
Posts: 174
Likes: 60
From: Miami
C63s Sedan
I have catless downpipes and just a couple of days ago I cut off the performance exhaust and put a straight pipe in its place to mimic the AWE track exhaust.
Not much drone, only around 1000-2000 RPM. Highway cruising when its in 6th & 7th gear is silent. Car is definitely louder cold start since there are no flaps.
Not much drone, only around 1000-2000 RPM. Highway cruising when its in 6th & 7th gear is silent. Car is definitely louder cold start since there are no flaps.
Thread Starter
Junior Member
Joined: Oct 2021
Posts: 23
Likes: 2
2021 C 63 S
I have catless downpipes and just a couple of days ago I cut off the performance exhaust and put a straight pipe in its place to mimic the AWE track exhaust.
Not much drone, only around 1000-2000 RPM. Highway cruising when its in 6th & 7th gear is silent. Car is definitely louder cold start since there are no flaps.
Not much drone, only around 1000-2000 RPM. Highway cruising when its in 6th & 7th gear is silent. Car is definitely louder cold start since there are no flaps.
Member
Joined: Apr 2017
Posts: 174
Likes: 60
From: Miami
C63s Sedan
Then I went catless downpipes from a vendor on this site, no heat shield, as he said it was not necessary. Installed myself then got a tune. Reversible as well. Double the pops and bangs. Same noise level during cold start and high RPMS but more pops.
Took it a step further with cutting out the performance exhaust mufflers. Also reversible.
So you have options, but Secondary cat delete + EVM will sound nice. It will always have that growl in lower RPMs but will sound stock at high RPMs. My setup is almost double at all RPM levels, similar to AWE track exhaust.
Last edited by miamiboy; Mar 21, 2022 at 03:29 PM.
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Thread Starter
Junior Member
Joined: Oct 2021
Posts: 23
Likes: 2
2021 C 63 S
So when I bought the car, I cut the 2nd cat out, it was definitely louder but only in the high RPMs and cold start. No CEL. A local guy cut it out and welded in pipes in 30 mins. Definitely reversible.
Then I went catless downpipes from a vendor on this site, no heat shield, as he said it was not necessary. Installed myself then got a tune. Reversible as well. Double the pops and bangs. Same noise level during cold start and high RPMS but more pops.
Took it a step further with cutting out the performance exhaust mufflers. Also reversible.
So you have options, but Secondary cat delete + EVM will sound nice. It will always have that growl in lower RPMs but will sound stock at high RPMs. My setup is almost double at all RPM levels, similar to AWE track exhaust.
Then I went catless downpipes from a vendor on this site, no heat shield, as he said it was not necessary. Installed myself then got a tune. Reversible as well. Double the pops and bangs. Same noise level during cold start and high RPMS but more pops.
Took it a step further with cutting out the performance exhaust mufflers. Also reversible.
So you have options, but Secondary cat delete + EVM will sound nice. It will always have that growl in lower RPMs but will sound stock at high RPMs. My setup is almost double at all RPM levels, similar to AWE track exhaust.
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Member
Joined: Apr 2017
Posts: 174
Likes: 60
From: Miami
C63s Sedan
I went to a muffler shop and tried to do a second cat delete, but the guy didn't seem like he knew what he's doing and only "knocked out the honey combs" and welded it back up. Do you have a picture of before and after the delete that I can refer to? Thanks a lot. Also, why did you go this route instead of switching to AWE?
I don’t have any pics of my secondary cat delete at this moment but if you skip to 5:30 in this video, it shows the section that was modified.
Your shop should cut right before the secondary cat and right after it. Then weld a short pipe to fill the gap. I think the pipe is 3 inches wide. Cost me $150 in Miami.
Thread Starter
Junior Member
Joined: Oct 2021
Posts: 23
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2021 C 63 S
Thanks man. looks like you were in 4th gear? Which one did you get the HJC or gesi 400? I got the 400 hoping to not need a tune for the CEL.
