[Khambinho]

So I just got a catless downpipe and heard that the smell is usually very noticeable and is also very loud.

For anyone with the same or similar setup:

1) How loud is it compared to carted with stock muffler

2) I know muffler is there to muffle sound but will the stock muffler help with toning down the smell at all?

2014 335i xdrive
-intake
-c pipe
- stock exhaust

[LA1Z24]

Stage 2 BM3 catless DP, no smell at all. None. Had VRSF race muffler, too loud...Went back to stock, too quiet. Opened up stock muffler, repacked it with ceramic packing, welded up some baffle holes, now shes perfect...for me. Also I have a resonator delete.

[chinniciF32]

Originally Posted by Khambinho

So I just got a catless downpipe and heard that the smell is usually very noticeable and is also very loud.

For anyone with the same or similar setup:

1) How loud is it compared to carted with stock muffler

2) I know muffler is there to muffle sound but will the stock muffler help with toning down the smell at all?

2014 335i xdrive
-intake
-c pipe
- stock exhaust

I have a highflow after market DP paired with the MPE (M Performance exhaust which is only slightly louder than the stock muffler) and cold starts are pretty loud, as far as driving around town in comfort you dont notice too much of a difference except a sporty growl when you get into the higher rpms.

In sport or sport+ with manual shifting it is definetly louder and sportier sounding but not raspy and when you shift at high rpms you get the cool "suck fart sounds" and a nice subtle growl.

The MPE is good if you want something a little bit louder, deeper, and sportier sounding but not over the top like AWE or the many other after market exhaust/muffler systems out there, by themselves the after market systems sound nice but when paired with a catlesss DP most people find them a little much.

As far as the smell even with highflow DP the smell in my garage is strong sometimes even so at long traffic lights, I can only imagine a catless DP would be worse, but you get used to it.

[Khambinho]

Do you guys have sound clips?

LA1Z24

chinniciF32

[thejeremyman9]

Originally Posted by LA1Z24

Stage 2 BM3 catless DP, no smell at all. None. Had VRSF race muffler, too loud...Went back to stock, too quiet. Opened up stock muffler, repacked it with ceramic packing, welded up some baffle holes, now shes perfect...for me. Also I have a resonator delete.

This is misleading. There is absolutely smell with a catless DP, it really just comes down to individual tolerance and how noticeable it is under certain driving conditions. Driving on the highway, sure, you probably wont smell it. But anytime you are at idle with no wind and not moving, the smell can easily come into the cabin with the windows down or HVAC on.

Originally Posted by Khambinho

So I just got a catless downpipe and heard that the smell is usually very noticeable and is also very loud.

For anyone with the same or similar setup:

1) How loud is it compared to carted with stock muffler

2) I know muffler is there to muffle sound but will the stock muffler help with toning down the smell at all?

2014 335i xdrive
-intake
-c pipe
- stock exhaust

There are dozens if not 100s of posts on your exact same question so i would suggest a search. Use google with this specific site if the forum search isnt working.

1. Its going to be louder and more raspy than OEM DP. I'm sure you can find videos on youtube.

2. No... the muffler has nothing to do this emissions.

[Pussiwillow]

I'm catless
I have to pull car out of garage immediately after starting or the smell gets into the house the moment you open the door; it doesn't bother me; and you don't smell in the car, you will smell it in a drive through with windows down or in traffic tho, it doesn't bother me, but it's very noticeable.

And yes it makes more noise, I have cold start off and gts roar set up through mhd, perfect, quiet starts. The elevated rpm at start is to warm the cat for emissions. No need for it now. It's a perfect sound with catless; stock exhaust

[thejeremyman9]

Originally Posted by Pussiwillow

I'm catless
I have to pull car out of garage immediately after starting or the smell gets into the house the moment you open the door; it doesn't bother me; and you don't smell in the car, you will smell it in a drive through with windows down or in traffic tho, it doesn't bother me, but it's very noticeable.

And yes it makes more noise, I have cold start off and gts roar set up through mhd, perfect, quiet starts. The elevated rpm at start is to warm the cat for emissions. No need for it now. It's a perfect sound with catless; stock exhaust

Disabling cold start does cause issues for some people. Seems to be hit and miss. I wouldn't disable it unless you absolutely need to for noise reasons.

[Pussiwillow]

Originally Posted by thejeremyman9

Disabling cold start does cause issues for some people. Seems to be hit and miss. I wouldn't disable it unless you absolutely need to for noise reasons.

Ahhh I didn't know that; I've been rocking it for 3 weeks without a problem, I guess I'm one or the lucky ones
I prefer it quiet because it's loud for the neighbor when it's in the garage initial start

[Tpriest7893]

Catless and stock muffler here. Only time I smell anything is if I'm standing behind my car while running. At red lights and around town I do not smell.

Pretty nice difference from stock as far as sound especially when you open it up. Comfort mode not much different

[thejeremyman9]

Originally Posted by Pussiwillow

Ahhh I didn't know that; I've been rocking it for 3 weeks without a problem, I guess I'm one or the lucky ones
I prefer it quiet because it's loud for the neighbor when it's in the garage initial start

If it works, it works. Some people just get rough idle, dips in RPM, etc, on cold starts without it. But you might be fine. The startup roar can help even with just that initial throttle blip.

[Pussiwillow]

Originally Posted by thejeremyman9

If it works, it works. Some people just get rough idle, dips in RPM, etc, on cold starts without it. But you might be fine. The startup roar can help even with just that initial throttle blip.

I can see that for sure, and I assumed the start up roar would help that, as you said

[mike@x-ph.com]

Originally Posted by Khambinho

So I just got a catless downpipe and heard that the smell is usually very noticeable and is also very loud.

For anyone with the same or similar setup:

1) How loud is it compared to carted with stock muffler

2) I know muffler is there to muffle sound but will the stock muffler help with toning down the smell at all?

2014 335i xdrive
-intake
-c pipe
- stock exhaust

im confused, why are you asking how it is when you say you already have it?

1) cold start is noticeably louder, after that its 20% louder
2) the muffler does not help with the smell. Catless will have a smell, the only way around it is to get a catted downpipe

[n55david]

Originally Posted by mike@x-ph.com

im confused, why are you asking how it is when you say you already have it?

1) cold start is noticeably louder, after that its 20% louder
2) the muffler does not help with the smell. Catless will have a smell, the only way around it is to get a catted downpipe

mine was 22% louder

[Khambinho]

Originally Posted by mike@x-ph.com

im confused, why are you asking how it is when you say you already have it?

1) cold start is noticeably louder, after that its 20% louder
2) the muffler does not help with the smell. Catless will have a smell, the only way around it is to get a catted downpipe

Its not installed yet

[Fthree6mafia]

Catted AA DP here paired with MPE. Cold starts are (were) loud, but then remedied with tune, and the smell is there but not terrible. For me, this combo provides the perfect balance. The MHD tune also provides option for exhaust valve open in sport mode, and I can dial in louder burbles in sport mode vs comfort. So I have a reasonably quiet car when wife and kids are in the car, but by myself I tap a button have MY car. Not too over the top, but sporty exotic sound when I want it, quiet enough but still sounds sick when in comfort. Also, stage 2+ power is crazy fun, only downside is now I need and LSD and good summer tires always to put power down effectively. Literally can brake the tires loose at 60 currently.

[harlen]

OK have ran mine for a few hundred Ks.

With an LSD, some Michelin Pilot Sport 4S, catless DP, CP, IC, and air filter upgrade, MDH 2+ XHP it feels like a new car. My god. That LSD corners with DSC off DTC on are a whole new experience.

With cold start delete, the car is plenty quiet. I drive out of an underground shared carpark that resonates my motorbikes to a 10+ obnoxiousness. The car can sneak out mostly silent, except when needing to give a little gas on upramps makes it bump up to a 2, but still fine.

When driving in eco the difference is definitely noticeable especially when accellerating even within 1/4-1/2 the eco pro guides. There's a thickness to the exhaust note even when keeping things below 1500-2000 at slow (sub 25mph) speeds. It's not obnoxious, I'd even say it's subtle, but it certainly isn't the quiet thing that it used to be. Someone on the street might side eye you, knowing you're hiding something At higher speeds it's fine because it gets masked by other noises. But if you get on a slight hill where it needs a bit of gas to maintain speed you will hear it inside.

In sport plus, sport mode, with MDH+XHP and OEM burble settings fanging it through some foresty twisties, it sounds good. From pure OEM i always felt like I wanted 20% more note in sporty driving, and it hass done that. Not as bassy loud as I was expecting (i'm a long time motorbike rider so that may impact expectations too). It's more... raspy? And the OEM burble setting is a chunk louder, and has gone from being perfectly subtle to a bit much for me. I've dropped mine from 1.2s to .8, and might drop it further or add a higher rev range.

Smell is very noticeable in an underground carpark. If just driving straight and with an easy park it's subtle. But I had to fiddle around squeezing into a spot for a minute and it stank awful when I got out. Only noticed it a couple of times in crawling traffic, when I had the windows down. Not at all when in smoother traffic.

And the exhaust tips are going to need some extra cleaning attention.

[SlumpLord3000]

My catless VRSF had a smell. Turning the burbles off helped since it's not throwing extra gas for the pops. It still smelled a bit after turning them off.

[yanboogie]

I run dp and stock exhaust, smells only when in an enclosed area. Even at a stop light I don't really smell it unless I was driving really hard before.

As for noises I really think it's quiet still but I'm used to being around 3-4" straight pipped evos and such. I think it's perfect if you're looking for a little more umph without a loud noise factor. I did disable cold start since im not tryna piss off my neighbors at 6am.

Turned down my burble duration to like .8 and aggressiveness was turned up. I'll most likely be turning duration down even further. Personally I rather have 1 loud pop as opposed to a few going off every time.

Pretty much on par with harlens experience. Although I feel as if I have an exhaust leak since i feel like mine should be a deeper tone than it is now. But that's a me problem as opposed to the setup problem.