[E85 Sport]

We are all familiar with ABC deletes. But some of us dislike the smoke, smell, and sounds that come with a “full delete.”

For those who prefer a stealth approach, what is the best blend of performance and efficiency for M57?

Likes:

• more power
• better cruising mpg's
• reduced carbon build-up
• quietness
• low effort, proven method

Dislikes:

• smoke
• smell
• loudness

[lnxguy]

Downpipe with DOC. I'd never call a deleted car loud, they sound like Dyson vacuums at idle.

[Tomnavigator]

E85 Sport here are my comments to your posting

Likes:

more power There is no way to gain any significant power without a performance tune which is not usually a low effort modification since most people delete the emissions equipment with the performance tune
better cruising mpg's - Better cruising MPG is usually gained by the EGR delete and the DPF delete. Again not a low effort change. Note: removal of the DPF requires removal of the SCR to prevent SCR plugging up.
reduced carbon build-up - Reduced carbon buildup is obtained by EGR delete. This can be done by disabling the EGR actuator (causes trouble codes), block off plates (causes trouble codes), and/or EGR delete tune (no trouble codes but costs money).
quietness - The car will remain quiet unless you remove the DOC, DPF, and SCR. Then it will be about 20% louder and you will hear a turbo whine when the engine speeds up and slows down. If you remove the DPF and SCR and leave the DOC the car will be slightly louder and you will faintly hear the turbo whine. But, your wife would not notice the difference. If you remove the resonators (the muffler looking canisters under the trunk) the car exhaust will not get louder but the exhaust will become harsh sounding usually at highway speeds. The exhaust will have a resonance noise which most people describe as a droning sound and find extremely annoying.
low effort, proven method. The only low effort thing you can do is the EGR block off and/or a performance tune with all emissions left intact. This would kill carbon build up and give you more power.


Dislikes:

smoke - You will not see any significant gain in smoke unless you install a performance tune and then will only see smoke when you floor it.
smell - Remove the SCR and the smell level will increase some. Remove the DOC and most people find the smell objectionable.
loudness - Addressed above already. DON'T remove the resonators.

The best thing to do for absolute dependability, MPG, and quietness would be to do an emissions delete tune without a performance tune removing the EGR cooler, leaving the DOC intact in the DPF, removing the DPF (filter part), removing the SCR, removing the DEF system, and leaving the resonators intact or replacing the resonators with true mufflers. Note: This is not a low effort solution.
Some will say that a performance tune will not significantly reduce the overall life of the engine and/or transmission. That is why I say for "absolute dependability" above.

[Nadir Point]

You know, the 2011 335D WAS the quickest car in the U.S. lineup that year. Based on your criteria, stock is really the only way to go.

[E85 Sport]

Originally Posted by lnxguy

Downpipe with DOC.

These are the two I find on the market.
Big difference in price.
Any difference in sound and smell?

1. ATM SpeedShop downpipe made of 304 stainless steel $495 + $275 DOC = $770
2. TuneMyEuro BuzzKen downpipe made of 409 stainless steel $920 + $610 DOC = $1,470

[E85 Sport]

Tomnavigator thank you for the informative, detailed reply!

To summarize your recommendation:

Best thing for absolute dependability, MPG, and quietness:

• emissions delete tune without a performance tune,
• remove the EGR cooler,
• remove DPF (filter part),
• remove SCR,
• remove DEF system,
• leave DOC intact,
• leave resonators intact or replace resonators with true mufflers

From a "low effort" perspective, I would rather buy ready-made parts than spend time cutting/gutting factory components or having something custom fabricated.

Does anybody make a center-section that replaces SCR and connects to factory rear cans (resonators)?

Do you have any thoughts on the DOC-equipped aftermarket downpipes I posted above?

Thanks for sharing your knowledge.

[E85 Sport]

Originally Posted by Nadir Point

You know, the 2011 335D WAS the quickest car in the U.S. lineup that year. Based on your criteria, stock is really the only way to go.

I don't need to be the fastest. I want to be the most reliable.

I am planning for 2023 and want to reduce the chance of costly issues from failure-prone components.

If there's an improvement in fuel economy or power, so be it. But that is secondary.

[Spyro235]

For what you want, the factory DOC, modified to remove the other half of the factory DPF, will be the best option. Personally, I like the sound, but not the smell. So I turn my car off if I'm kneeling hitching a trailer. Otherwise, unless I'm backing up with my windows down, I never notice the smell. I'm very sensitive too it, too.
The factory DOC (half the DPF) is the absolute best DOC available. It will quell most of the turbo noise you seek to stay away from, and should cut down on any "smoke " you might see.

Otherwise, the factory muffler is not much of a muffler. Putting real mufflers on the car could help a lot.

For reliability, you need to delete the failure prone stuff. There wont really be a difference in reliability between a normal delete tune and a mild performance one, these motors are tried and true and a few pounds of boost isnt going to unearth any different problems in your vehicle.

[Suvorovo]

I'm not going to lie, I love the diesel exhaust smell from my friend's modded msport 335d.

[BB_cuda]

Originally Posted by E85 Sport

These are the two I find on the market.
Big difference in price.
Any difference in sound and smell?

1. ATM SpeedShop downpipe made of 304 stainless steel $495 + $275 DOC = $770
2. TuneMyEuro BuzzKen downpipe made of 409 stainless steel $920 + $610 DOC = $1,470

I have direct experience with both. Buzzken is on our 2013/X5D and ATM one on 2011/335D. Both have DOCs. The 304 SS material on ATM unit is superior to corrosion resistance. I bought the Buzzken unit in Dec 2017 and the ATM one in Nov 2020. I have heard that since that time that the Buzzken unit has had an upgrade to its DOC and works even better now. I can't confirm this though as I have the older DOC that is 5 yrs old.

Another poster spoke to gutting a DPF but keeping the DOC in tact. I did this same thing and can confirm that without a doubt this method has WAAAYY cleaner smell than the others I discuss above. I ultimately pulled it to get a better flow and more sound from the ATM unit. I still have the gutted DPF on my parts shelf.

[Tomnavigator]

I agree with BB_Cuda. 304SS is a very corrosion resistant stainless steel. 400 series stainless steel are cheap not very corrosion resistant stainless steel. 409ss is used in automotive exhaust and will probably last the life of the vehicle. 304ss is much more expensive and has much more chromium as 409ss. One way to tell the difference is that 409 series stainless steel is magnetic (a magnet will stick). 304SS is nonmagnetic.