540i Mods and Questions

KevsG30 · 06-04-2025, 12:19 AM

I drive a 2021 540i (RWD) and had a few things I wanted to ask or share. Appreciate any feedback

First I’m thinking of getting a downpipe. I want something that makes the car a bit louder but not catless. I don’t want it to trigger a CEL. I’m in California but I don’t care about emissions. I was looking at Active Autowerke’s catted downpipe. If anyone’s using that or has a better option that sounds clean and doesn’t throw codes, let me know

Second I have the MST intake installed and it’s been great. Sound is solid and throttle feels better. Now I’m thinking of swapping the filter for a PRORAM cone with a velocity stack. A friend of mine told me it makes the turbo noises even louder and maybe flow better. Has anyone here tried that setup on the MST pipe

Third I’m planning to tune the car (most likely JB4) later on but right now it’s stock. I’m wondering if it’s fine to run XHP by itself. I feel like the car loses momentum during shifts and I’m hoping Stage 2 can fix that even without an engine tune. Anyone running XHP on stock power.

Not looking to make this a beast, but definitely wake the car up with sound and performance.

mike@x-ph.com · 06-04-2025, 11:24 AM

the active autowerke downpipe is an excellent option for more sound and power without the check engine light.

DarthBMR · 06-04-2025, 12:08 PM

Can't speak for the other mods but I have a JB4 on my '21 540i........incredible! The way the car should be!! Best bang for the buck imo!

KevsG30 · 06-04-2025, 11:53 PM

Quote:

Originally Posted by DarthBMR

Can't speak for the other mods but I have a JB4 on my '21 540i........incredible! The way the car should be!! Best bang for the buck imo!

How long have you had the JB4? Any issues you've experienced?

Jason73 · 06-05-2025, 04:53 AM

I have a 2019 540. Started off with Active downpipe and JB4. Switch JB4 to MHD and do not regret it at all. More power and much smoother. Several additional changes available that can be made and more maps for future mods.

DarthBMR · 06-05-2025, 10:21 AM

Quote:

Originally Posted by KevsG30

How long have you had the JB4? Any issues you've experienced?

Ive put on about 4000 miles so far, it's been perfect! No issues.

mike@x-ph.com · 06-05-2025, 01:22 PM

Quote:

Originally Posted by DarthBMR

Ive put on about 4000 miles so far, it's been perfect! No issues.

06-04-2025, 12:19 AM	#1
KevsG30 Registered 0 Rep 4 Posts Drives: 2021 540i Join Date: Dec 2024 Location: CA iTrader: (0)	540i Mods and Questions I drive a 2021 540i (RWD) and had a few things I wanted to ask or share. Appreciate any feedback First I’m thinking of getting a downpipe. I want something that makes the car a bit louder but not catless. I don’t want it to trigger a CEL. I’m in California but I don’t care about emissions. I was looking at Active Autowerke’s catted downpipe. If anyone’s using that or has a better option that sounds clean and doesn’t throw codes, let me know Second I have the MST intake installed and it’s been great. Sound is solid and throttle feels better. Now I’m thinking of swapping the filter for a PRORAM cone with a velocity stack. A friend of mine told me it makes the turbo noises even louder and maybe flow better. Has anyone here tried that setup on the MST pipe Third I’m planning to tune the car (most likely JB4) later on but right now it’s stock. I’m wondering if it’s fine to run XHP by itself. I feel like the car loses momentum during shifts and I’m hoping Stage 2 can fix that even without an engine tune. Anyone running XHP on stock power. Not looking to make this a beast, but definitely wake the car up with sound and performance.
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06-04-2025, 11:24 AM	#2
mike@x-ph.com Joint Chiefs of Staff 30218 Rep 201,626 Posts Drives: 07-335/12-328/18-M4/21-M4CP Join Date: Sep 2013 Location: Las Vegas iTrader: (23)	the active autowerke downpipe is an excellent option for more sound and power without the check engine light. __________________ Check out our current sale by clicking on this link! https://x-ph.com/sale/ Phone number 702-494-9435
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06-04-2025, 12:08 PM	#3
DarthBMR New Member 2 Rep 8 Posts Drives: 2021 540i M-Sport Join Date: Feb 2025 Location: DFW iTrader: (0)	Can't speak for the other mods but I have a JB4 on my '21 540i........incredible! The way the car should be!! Best bang for the buck imo!
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06-05-2025, 04:53 AM	#5
Jason73 Private First Class 107 Rep 148 Posts Drives: 2022 X3 M40i Join Date: May 2017 Location: South Carolina iTrader: (0)	I have a 2019 540. Started off with Active downpipe and JB4. Switch JB4 to MHD and do not regret it at all. More power and much smoother. Several additional changes available that can be made and more maps for future mods.
	Appreciate 0 Quote