Anyone actually installed Catted DP's and found them to be good?

[mmmmQuattro]

From what I have searched on the forums, catted dp's offer very little performance gain and provide a bit more sound.
I had catless dp's on my 335 and there was a bit of smell, but the noise was fantastic.
Also guys that have had catless dp's on 335's and now have them on the M3/4, say that the smell isn't as much.
Can anyone comment on that please?
Thanks,
Jp.

[Arcades]

Originally Posted by jp330Cic.au

From what I have searched on the forums, catted dp's offer very little performance gain and provide a bit more sound.
I had catless dp's on my 335 and there was a bit of smell, but the noise was fantastic.
Also guys that have had catless dp's on 335's and now have them on the M3/4, say that the smell isn't as much.
Can anyone comment on that please?
Thanks,
Jp.

The DP setup on F8x are different from the F3x.

I'm pretty certain if you do straight DP w/ Stock Exhaust, the smell won't be that bad since you're retaining all of the cats in the middle. F3x exhausts aren't the same. F3x is about half the section of compared to how the F8x exhausts are.

So your friend is right. The smell would only get worse if you change rear and mid as well, going full length.

I gotten to know this pretty well since I been going back and forth on my decisions for a month + now.

supremepower or tom @ eas or Alex from ACM West, or anyone really can correct me if I'm wrong.

[ShlemonboostedM]

Smell is still horrible with catless dp and stock exhaust .. I thought it won't be as their still cats in the mid pipe .. But it still smell pretty bad ...

[M4RAUDR]

Originally Posted by jp330Cic.au

From what I have searched on the forums, catted dp's offer very little performance gain and provide a bit more sound.
I had catless dp's on my 335 and there was a bit of smell, but the noise was fantastic.
Also guys that have had catless dp's on 335's and now have them on the M3/4, say that the smell isn't as much.
Can anyone comment on that please?
Thanks,
Jp.

I can only speak for a full exhaust replacement with catless dp's. The smell is bothersome - no two ways about it. If you start your car in the garage - even if you back out immediately - the garage will be full of fumes. If you are moving 30+ mph and your windows are down, you are usually ok. Slower speeds and idling with windows down, you will get annoying fumes. It's not even so much just the smell - it's that it can give you a nasty headache really fast - the fumes are potent. Windows up solves all problems and you don't notice them at all. It's definitely a tradeoff. Sounds great, but you pay a price.

[schnazzy]

I have catless DPs and the MPE which retains the 2nd cats. No rotten smell. I was told by people who have done it, that taking the 2nds out will smell bad. This info is only for the M4. I don't know about other cars (335 etc.)

[Arcades]

Originally Posted by schnazzy

I have catless DPs and the MPE which retains the 2nd cats. No rotten smell. I was told by people who have done it, that taking the 2nds out will smell bad. This info is only for the M4. I don't know about other cars (335 etc.)

Any car with an exhaust system setup like a F8x (full length, rear, mid and downpipes) will be the same. F30x or any more mainstream car models (4, 5 series etc) won't go this far when it comes to exhausts.

It depends on how you handle the fumes, some people can, some can't. If you have the habit of keeping your windows up then it honestly might not matter. I was around TwinMTurbo car for a few and he kept his rear section with Mid AA + DPs and I wasn't bothered much by the fumes but we were outside then so take that as it is.

If you keep rear or mid stock, the fumes shouldn't be EXTREME, but you will still smell it because you changed the downpipes.

As long as you change the DPs, you will smell the fumes regardless. Then there is the whole engine check light and SMOG if you plan to keep your car long term like me.

[tom @ eas]

Originally Posted by jp330Cic.au

From what I have searched on the forums, catted dp's offer very little performance gain and provide a bit more sound.
I had catless dp's on my 335 and there was a bit of smell, but the noise was fantastic.
Also guys that have had catless dp's on 335's and now have them on the M3/4, say that the smell isn't as much.
Can anyone comment on that please?
Thanks,
Jp.

We're running an Akrapovic Evolution system and ER Catless downpipes on our shop M4 (sans cats) and have no issues with fuel smell, some may be a bit more sensitive than others.

If this is still a concern, its best to keep the stock midpipe, there are no performance benefits to changing if keeping stock turbos. A stock exhaust with caqtless downpipes sounds pretty good on its own, especially with a controllable exhaust flap like the Macht Schnell EVC module.

[supremepower]

Well the F3x is a single downpipe to a single pipe with a resonator to the muffler vs the F8x with a primary cat, to dual secondary cats. If you decide to do downpipes with the stock exhaust, the smell isn't too bad

We highly recommend downpipes with the stock exhaust OR doing the Active midpipe for added sound without any unattractive smells

[GOLFFRR]

I run the akra EVO with ER catless DPs and I rarely ever have the smell. The only time I ever smell it is when I pull into my garage and the car is idling for a few moments then I get a brief smell but nothing crazy. Maybe i just am use to it I don't know but I have had no issues so far

[M4 CSL]

Originally Posted by GOLFFRR

I run the akra EVO with ER catless DPs and I rarely ever have the smell. The only time I ever smell it is when I pull into my garage and the car is idling for a few moments then I get a brief smell but nothing crazy. Maybe i just am use to it I don't know but I have had no issues so far

Same, I run Akra DP and akra Evo. The only time I get a breif wiff is when I first start up in the garage if windows down. Never smell anything when moving.

Being a child of the 70's I'm used to petrol fumes. I don't understand the delicate petals of today.

I remember the days of diesel trucks and buses bellowing black soot into your car as they went past, as no air con in those days in most cars. If a bus was coming everyone would hurry to wind up the windows as it went past..

But the kids of today are wrapped in cotton wool.

[singh21]

I have a catless convertible and dont get much smell at all. Even with roof down

[Mike@N54Tuning.com]

I never found the smell from catless downpipes to be an issue, but like mentioned above different people have different sensitivities. I would say unless you are overly sensitive there should be no issue with smell.

Mike

[mmmmQuattro]

Originally Posted by supremepower

We highly recommend downpipes with the stock exhaust OR doing the Active midpipe for added sound without any unattractive smells

The Active midpipe sounds interesting, but from what I can see, it deletes the secondary cats - is this right?

[supremepower]

Originally Posted by jp330Cic.au

The Active midpipe sounds interesting, but from what I can see, it deletes the secondary cats - is this right?

Yes, it does delete the secondary cats

[mike@x-ph.com]

Originally Posted by jp330Cic.au

The Active midpipe sounds interesting, but from what I can see, it deletes the secondary cats - is this right?

Catless DP with Active midpipe sounds amazing

[Alvinized52]

Originally Posted by supremepower

Well the F3x is a single downpipe to a single pipe with a resonator to the muffler vs the F8x with a primary cat, to dual secondary cats. If you decide to do downpipes with the stock exhaust, the smell isn't too bad

We highly recommend downpipes with the stock exhaust OR doing the Active midpipe for added sound without any unattractive smells

I want to change the exhaust tone of my car but cant justify buying an expensive exhaust system. Not quite sure if I want to do catless DP either. I would like it to be slightly deeper and louder than stock but no drone. Are you saying if I keep stock DP and stock exhaust... but change to Active midpipe, the sound will change tone?

Also, Will i have issues passig Smog testing later on without 2nd cat?

[Mike@N54Tuning.com]

Originally Posted by Alvinized52

I want to change the exhaust tone of my car but cant justify buying an expensive exhaust system. Not quite sure if I want to do catless DP either. I would like it to be slightly deeper and louder than stock but no drone. Are you saying if I keep stock DP and stock exhaust... but change to Active midpipe, the sound will change tone?

Also, Will i have issues passig Smog testing later on without 2nd cat?

Catless downpipes while leaving the the stock exhaust and mid pipes will give you the sound you are describing.. Great combination.

Mike

[mike@x-ph.com]

Originally Posted by Alvinized52

I want to change the exhaust tone of my car but cant justify buying an expensive exhaust system. Not quite sure if I want to do catless DP either. I would like it to be slightly deeper and louder than stock but no drone. Are you saying if I keep stock DP and stock exhaust... but change to Active midpipe, the sound will change tone?

Also, Will i have issues passig Smog testing later on without 2nd cat?

replacing midpipes only will change the tone.
You will still pass OBD emission test but might run into problems with the sniffer test

[tom @ eas]

Had a lengthy discussion with the team from Akrapovic during their visit from Slovenia at our facility. Some very exciting things coming through the pipeline.

They are considering offering a 200cpsi catted version of the S55 downpipes.

[A Frankfurt]

Originally Posted by Alvinized52

I want to change the exhaust tone of my car but cant justify buying an expensive exhaust system. Not quite sure if I want to do catless DP either. I would like it to be slightly deeper and louder than stock but no drone. Are you saying if I keep stock DP and stock exhaust... but change to Active midpipe, the sound will change tone?

Also, Will i have issues passig Smog testing later on without 2nd cat?

For catless downpipes you will need either JB4 / Macht Schnell / Akrapovic module to clear the CEL that will be present.
For the secondary cat being removed, if a legit smog station actually checked under your car then yes you would fail by inspection.
Some check the cars and some don't. That is the risk but the system is very easy to revert to stock so I would recommend to do that before taking a chance.