[Fahadbs]

Folks, I too suffer from the infamous whistling sound that occurs under WOT past 4K RPMs. Started right after MPE install on my 2016 435i xDrive. Have scoured every post I could find on the forum and not yet have I seen a verified fix for it. The closest one was “try removing / adjusting the exhaust tips” and that didn’t work either.

Today my local dealer decided to order a new MPE after spending 4 hours diagnosing and adjusting it, but to no avail. I told the dealer that a replacement is likely not going to fix this but I am okay testing this hypothesis.

So simple question for you, especially those that at some point were plagued with this same issue: what is the fix for this? How did you rectify this?

I know going back to stock will fix the issue but hoping to make the MPE work. Also note that I have no desire to do any other modifications to address this as I don’t want to void my certified warranty in any way.

Thx!

[pongkin]

check the valve

[Fahadbs]

Originally Posted by pongkin

check the valve

Fully functioning. Opens and closes as designed. Opens completely. Tested this myself and had the tech test this as well.

[XutvJet]

It's not the internals of the MPE. It's the improved flow/less sound damping. What you're hearing is the air going supersonic as it blows past the wastegate flap edges when the DME opens it to manage boost. You'll hear this sound more often when it's hot out (can't tell you why it's that way). There's no fix.

[Fahadbs]

Originally Posted by XutvJet

It's not the internals of the MPE. It's the improved flow/less sound damping. What you're hearing is the air going supersonic as it blows past the wastegate flap edges when the DME opens it to manage boost. You'll hear this sound more often when it's hot out (can't tell you why it's that way). There's no fix.

Yeah I read this in the other posts as well! Thought if I ask the question again, I could get a different answer. Wishful thinking I guess. Really disappointed by the MPE because of this annoying howling. I might end up taking it off and sell it on this forum. Haven’t made up my mind yet.

[badbread]

This noise?

[Fahadbs]

Originally Posted by badbread

This noise?

No. Mine is more of a whistling sound. Definitely not this sound in the video.

[badbread]

Originally Posted by Fahadbs

No. Mine is more of a whistling sound. Definitely not this sound in the video.

Damnit, thought we finally figured it out chaungo

[lens]

Originally Posted by badbread

Damnit, thought we finally figured it out chaungo

[Fahadbs]

So got a new replacement MPE put on by the dealer. Problem still persists. Dealer said they cannot do anything and this has been chalked up to “completely normal”. I can’t be driving around with this annoying sound so will be selling my MPE that now has a total of 50 miles on it.

Which other exhausts should I consider?

[thejeremyman9]

Originally Posted by Fahadbs

Which other exhausts should I consider?

Stock, modified.

https://f30.bimmerpost.com/forums/sh...d.php?t=819125

[Fahadbs]

Originally Posted by thejeremyman9

Stock, modified.

https://f30.bimmerpost.com/forums/sh...d.php?t=819125

How much should I expect in labor to get this done from a good Indy shop?

[Munchi435i]

Or just do a resonator delete and an upgraded downpipe with stock axelback exhaust

[thejeremyman9]

Originally Posted by Fahadbs

How much should I expect in labor to get this done from a good Indy shop?

Not sure, most DIY. But if you don't have a welder, I imagine it shouldnt take more than 2 hours to drop the exhaust, modify, and remount. So maybe $200?

[Fahadbs]

Originally Posted by Munchi435i

Or just do a resonator delete and an upgraded downpipe with stock axelback exhaust

What are good upgraded DP options?

[Fahadbs]

Originally Posted by thejeremyman9

Not sure, most DIY. But if you don't have a welder, I imagine it shouldnt take more than 2 hours to drop the exhaust, modify, and remount. So maybe $200?

Sounds very economical

[thejeremyman9]

Originally Posted by Fahadbs

What are good upgraded DP options?

There are tons of options. Basically depends if you want catless or catted and what your budget is. Cheapest catless is VRSF at about $250. Maximum performance benefit from catless, but you have to deal with the smell and emissions issues if you are in a strict state. Other end of the spectrum is fabspeed catted DP, which is 90+% of the performance benefit of catless, but a hefty $1400 price tag.

I'll try to post some info i have compiled in an excel file below as plain text and see if it works. The formatting wont be great but its basically:

<type> <manufacturer> <description> <price> <link>

Catless DP	VRSF	VRSF CATLESS DOWNPIPE 2012+ BMW N55 M135I/M235I/335I/435I/M2 F20/F21/F22/F30/F32/F33	$249.99	https://x-ph.com/vrsf-catless-downpipe-2012-bmw-n55-m135i-m235i-335i-435i-m2-f20-f21-f22-f30-f32-f33/
Catless DP	Wagner	WAGNER TUNING BMW F CHASSIS N55 DOWNPIPE	$390.00	https://x-ph.com/wagner-tuning-bmw-f-chassis-n55-downpipe/
Catless DP	Megan Racing	MEGAN RACING BMW N55 F22/F30/F32/F87 M235I/335I/ 335IXI/435I/435XI/M2 2016+ (EXCLUDES 2012-JULY 2013) DOWNPIPE	$399.99	https://x-ph.com/megan-racing-bmw-n55-f22-f30-f32-f87-m235i-335i-335ixi-435i-435xi-m2-2016-excludes-2012-july-2013-downpipe/
Catless DP	ER	EVOLUTION RACEWERKS ( ER) N55 DOWNPIPES M235/335/435/M2	$465.50	https://x-ph.com/evolution-racewerks-er-n55-downpipes-m235-335-435-m2/
Catless DP	Enzo	ENZO PERFORMANCE BMW N55 4" CATLESS DOWNPIPE	$599.00	https://x-ph.com/enzo-performance-bmw-n55-4-catless-downpipe/
Catless DP	Agency Power	AGENCY POWER DOWNPIPE BMW 335I 435I F30 SERIES	$600.00	https://x-ph.com/agency-power-downpipe-bmw-335i-435i-f30-series/
Catted DP	VRSF	VRSF CATTED DOWNPIPE 2012+ BMW N55 M135I/M235I/335I/435I/M2 F20/F21/F22/F30/F32/F33	$399.99	https://x-ph.com/vrsf-catless-downpipe-2012-bmw-n55-m135i-m235i-335i-435i-m2-f20-f21-f22-f30-f32-f33/
Catted DP	Wagner	WAGNER TUNING BMW F CHASSIS N55 DOWNPIPE	$790.00	https://x-ph.com/wagner-tuning-bmw-f-chassis-n55-downpipe/
Catted DP	ER	EVOLUTION RACEWERKS ( ER) N55 DOWNPIPES M235/335/435/M2	$825.50	https://x-ph.com/evolution-racewerks-er-n55-downpipes-m235-335-435-m2/
Catted DP	FI	FREQUENCY INTELLIGENT (FI) BMW F CHASSIS N55 CATTED DOWNPIPE	$1,050.00	https://x-ph.com/frequency-intelligent-fi-bmw-f-chassis-n55-catted-downpipe/
Catted DP	Agency Power	AGENCY POWER DOWNPIPE BMW 335I 435I F30 SERIES	$1,250.00	https://x-ph.com/agency-power-downpipe-bmw-335i-435i-f30-series/
Catted DP	Fabspeed	FABSPEED M235 / 335 / 435 / M2 DOWNPIPES	$1,395.00	https://x-ph.com/fabspeed-m235-335-435-m2-downpipes/

[Fahadbs]

Originally Posted by thejeremyman9

There are tons of options. Basically depends if you want catless or catted and what your budget is. Cheapest catless is VRSF at about $250. Maximum performance benefit from catless, but you have to deal with the smell and emissions issues if you are in a strict state. Other end of the spectrum is fabspeed catted DP, which is 90+% of the performance benefit of catless, but a hefty $1400 price tag.

I'll try to post some info i have compiled in an excel file below as plain text and see if it works. The formatting wont be great but its basically:

<type> <manufacturer> <description> <price> <link>

Catless DP	VRSF	VRSF CATLESS DOWNPIPE 2012+ BMW N55 M135I/M235I/335I/435I/M2 F20/F21/F22/F30/F32/F33	$249.99	https://x-ph.com/vrsf-catless-downpipe-2012-bmw-n55-m135i-m235i-335i-435i-m2-f20-f21-f22-f30-f32-f33/
Catless DP	Wagner	WAGNER TUNING BMW F CHASSIS N55 DOWNPIPE	$390.00	https://x-ph.com/wagner-tuning-bmw-f-chassis-n55-downpipe/
Catless DP	Megan Racing	MEGAN RACING BMW N55 F22/F30/F32/F87 M235I/335I/ 335IXI/435I/435XI/M2 2016+ (EXCLUDES 2012-JULY 2013) DOWNPIPE	$399.99	https://x-ph.com/megan-racing-bmw-n55-f22-f30-f32-f87-m235i-335i-335ixi-435i-435xi-m2-2016-excludes-2012-july-2013-downpipe/
Catless DP	ER	EVOLUTION RACEWERKS ( ER) N55 DOWNPIPES M235/335/435/M2	$465.50	https://x-ph.com/evolution-racewerks-er-n55-downpipes-m235-335-435-m2/
Catless DP	Enzo	ENZO PERFORMANCE BMW N55 4" CATLESS DOWNPIPE	$599.00	https://x-ph.com/enzo-performance-bmw-n55-4-catless-downpipe/
Catless DP	Agency Power	AGENCY POWER DOWNPIPE BMW 335I 435I F30 SERIES	$600.00	https://x-ph.com/agency-power-downpipe-bmw-335i-435i-f30-series/
Catted DP	VRSF	VRSF CATTED DOWNPIPE 2012+ BMW N55 M135I/M235I/335I/435I/M2 F20/F21/F22/F30/F32/F33	$399.99	https://x-ph.com/vrsf-catless-downpipe-2012-bmw-n55-m135i-m235i-335i-435i-m2-f20-f21-f22-f30-f32-f33/
Catted DP	Wagner	WAGNER TUNING BMW F CHASSIS N55 DOWNPIPE	$790.00	https://x-ph.com/wagner-tuning-bmw-f-chassis-n55-downpipe/
Catted DP	ER	EVOLUTION RACEWERKS ( ER) N55 DOWNPIPES M235/335/435/M2	$825.50	https://x-ph.com/evolution-racewerks-er-n55-downpipes-m235-335-435-m2/
Catted DP	FI	FREQUENCY INTELLIGENT (FI) BMW F CHASSIS N55 CATTED DOWNPIPE	$1,050.00	https://x-ph.com/frequency-intelligent-fi-bmw-f-chassis-n55-catted-downpipe/
Catted DP	Agency Power	AGENCY POWER DOWNPIPE BMW 335I 435I F30 SERIES	$1,250.00	https://x-ph.com/agency-power-downpipe-bmw-335i-435i-f30-series/
Catted DP	Fabspeed	FABSPEED M235 / 335 / 435 / M2 DOWNPIPES	$1,395.00	https://x-ph.com/fabspeed-m235-335-435-m2-downpipes/

This is awesome! Really helpful.

I think I will stick to catted DP.

[Fahadbs]

Originally Posted by thejeremyman9

There are tons of options. Basically depends if you want catless or catted and what your budget is. Cheapest catless is VRSF at about $250. Maximum performance benefit from catless, but you have to deal with the smell and emissions issues if you are in a strict state. Other end of the spectrum is fabspeed catted DP, which is 90+% of the performance benefit of catless, but a hefty $1400 price tag.

I'll try to post some info i have compiled in an excel file below as plain text and see if it works. The formatting wont be great but its basically:

<type> <manufacturer> <description> <price> <link>

Catless DP	VRSF	VRSF CATLESS DOWNPIPE 2012+ BMW N55 M135I/M235I/335I/435I/M2 F20/F21/F22/F30/F32/F33	$249.99	https://x-ph.com/vrsf-catless-downpipe-2012-bmw-n55-m135i-m235i-335i-435i-m2-f20-f21-f22-f30-f32-f33/
Catless DP	Wagner	WAGNER TUNING BMW F CHASSIS N55 DOWNPIPE	$390.00	https://x-ph.com/wagner-tuning-bmw-f-chassis-n55-downpipe/
Catless DP	Megan Racing	MEGAN RACING BMW N55 F22/F30/F32/F87 M235I/335I/ 335IXI/435I/435XI/M2 2016+ (EXCLUDES 2012-JULY 2013) DOWNPIPE	$399.99	https://x-ph.com/megan-racing-bmw-n55-f22-f30-f32-f87-m235i-335i-335ixi-435i-435xi-m2-2016-excludes-2012-july-2013-downpipe/
Catless DP	ER	EVOLUTION RACEWERKS ( ER) N55 DOWNPIPES M235/335/435/M2	$465.50	https://x-ph.com/evolution-racewerks-er-n55-downpipes-m235-335-435-m2/
Catless DP	Enzo	ENZO PERFORMANCE BMW N55 4" CATLESS DOWNPIPE	$599.00	https://x-ph.com/enzo-performance-bmw-n55-4-catless-downpipe/
Catless DP	Agency Power	AGENCY POWER DOWNPIPE BMW 335I 435I F30 SERIES	$600.00	https://x-ph.com/agency-power-downpipe-bmw-335i-435i-f30-series/
Catted DP	VRSF	VRSF CATTED DOWNPIPE 2012+ BMW N55 M135I/M235I/335I/435I/M2 F20/F21/F22/F30/F32/F33	$399.99	https://x-ph.com/vrsf-catless-downpipe-2012-bmw-n55-m135i-m235i-335i-435i-m2-f20-f21-f22-f30-f32-f33/
Catted DP	Wagner	WAGNER TUNING BMW F CHASSIS N55 DOWNPIPE	$790.00	https://x-ph.com/wagner-tuning-bmw-f-chassis-n55-downpipe/
Catted DP	ER	EVOLUTION RACEWERKS ( ER) N55 DOWNPIPES M235/335/435/M2	$825.50	https://x-ph.com/evolution-racewerks-er-n55-downpipes-m235-335-435-m2/
Catted DP	FI	FREQUENCY INTELLIGENT (FI) BMW F CHASSIS N55 CATTED DOWNPIPE	$1,050.00	https://x-ph.com/frequency-intelligent-fi-bmw-f-chassis-n55-catted-downpipe/
Catted DP	Agency Power	AGENCY POWER DOWNPIPE BMW 335I 435I F30 SERIES	$1,250.00	https://x-ph.com/agency-power-downpipe-bmw-335i-435i-f30-series/
Catted DP	Fabspeed	FABSPEED M235 / 335 / 435 / M2 DOWNPIPES	$1,395.00	https://x-ph.com/fabspeed-m235-335-435-m2-downpipes/

Also, I should clarify the reason for going with a catted. Based on what I have read catted will be quieter compared to a catless and I don't want my setup to become very loud.

[Munchi435i]

Originally Posted by Fahadbs

Also, I should clarify the reason for going with a catted. Based on what I have read catted will be quieter compared to a catless and I don't want my setup to become very loud.

If you are getting the resonator delete and stock axelback then I'd say go with cates because it will be very quiet with a catted dp. But I'd say start with the resonator delete and see how you like it.

[Fahadbs]

Originally Posted by Munchi435i

If you are getting the resonator delete and stock axelback then I'd say go with cates because it will be very quiet with a catted dp. But I'd say start with the resonator delete and see how you like it.

Understood. Thx. Also, I know that many folks take a conservative approach to modifications to avoid any impact to warranty. I Michigan I find the dealers to apply extra scrutiny. However, based on what I understand of the exhaust mechanics and what I have gathered from the forum, I don't think that exhaust related mods will give the dealer a reason to void electrical or Powertrain warranty. If they try to void the warranty, the burden of proof will be on them, right? I could be wrong but that is how I am approaching this. Thoughts on this topic?

[thejeremyman9]

Originally Posted by Fahadbs

Understood. Thx. Also, I know that many folks take a conservative approach to modifications to avoid any impact to warranty. I Michigan I find the dealers to apply extra scrutiny. However, based on what I understand of the exhaust mechanics and what I have gathered from the forum, I don't think that exhaust related mods will give the dealer a reason to void electrical or Powertrain warranty. If they try to void the warranty, the burden of proof will be on them, right? I could be wrong but that is how I am approaching this. Thoughts on this topic?

You can usually get away with a intake and axle back exhaust, but with any modification, you can get screwed, so it really is at your own risk. Typically, they will only void the warranty for items directly impacted by the modification. So if you put an exhaust and a window switch breaks, you wont have an issue... but if you put an intake and your MAF sensor acts weird, they will probably blame the intake.

Tune and DP will mostly likely ruin any chance of powertrain coverage.