vince92615

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!

MagnoC63Coupe

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.

vince92615

Nice man. I assume you got the heatshield with gen2? How much did you cost you for the whole thing with installation like 4k? you have a video of the sound? appreciate it.

vince92615

bump

miamiboy

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.

vince92615

THanks. I thought about doing the same, but I really like the original exhaust sound. I thought when you do emotional start, the flap is automatically opened? Eitherway, I have the EVM so the flap is always opened. I just wish the volume was louder.

miamiboy

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.

vince92615

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?

miamiboy

I already had the catless downpipes which AWE doesnt include so it didnt justify paying $2000 for only one small section I really needed.

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.

vince92615

bump. anyone else modded their 21?

MagnoC63Coupe

Here's a sound clip under medium acceleration with the Redstar Downpipes. I have the CEL due to running no tune yet. I will upload some more sound clips within a day or so.

vince92615

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.

MagnoC63Coupe

I got the Competition (Catless).

vince92615

o wow, so mine prolly wont sound anything like it.