[gtazu]

My warranty runs out in a couple weeks and I'm interested in maybe tuning my 2021 BMW 540i. Originally I was going to go the Femto and BM3 route but I really don't want to spend $1,500 since I'm starting college in the fall. Is a used JB4 from facebook marketplace worth it, or should I wait for the unlock and BM3 tune?

[gtazu]

Also I feel it is important to add that I also plan on getting a catless downpipe

[mike@x-ph.com]

if you are getting catless downpipe, you need a flash tune like bootmod3 or else you will get a check engine light.

If you are going to go with the Jb4, I recommend you get the active autowerke high flow catted downpipe to avoid the CEL.

the jb4 is certainly worth it as it takes your car to the next level power wise for a bargain price.

[drive_to_survive]

I think for most people a piggyback tune ends up as a stepping stone in their tuning journey and after some time you end up posting at a marketplace for your device.

Nothing wrong with that.

I went through a similar path for my 2021 540i, but had I experienced a stage 2 car before hand, I would have skipped the piggyback.

First, had an aa catted downpipe + race chip.
The power bump was noticeable and well worth the money. ( later read up that downpipe upgrade without a tune is not recommended).

Post new car warranty expiry(CPO still intact) hesitantly went for femto unlock and went stage 2 + Xhp.

The gains were massive in terms of smoothness and power.

My advice, if you can squeeze in the femto unlock, go for that, even if stage 1.

As for your specific question, yes a jb4 is well worth the money, but try to buy a new one with proper support from the company.

[will4ya]

I have a 2021 as well, I put a JB4 on it and a Dinan drop in filter and l love it so far. I'm currently saving up for a AA catted downpipe and that will be it for me as reliability is more important at the moment and I'm still under warranty. But in the future, if Femto becomes cheaper or the technology makes it to the states, I will look into it as Im not willing to ship my ECU or have to repeat the process if the dealership does a update on my vehicle.

[mike@x-ph.com]

Originally Posted by will4ya

I have a 2021 as well, I put a JB4 on it and a Dinan drop in filter and l love it so far. I'm currently saving up for a AA catted downpipe and that will be it for me as reliability is more important at the moment and I'm still under warranty. But in the future, if Femto becomes cheaper or the technology makes it to the states, I will look into it as Im not willing to ship my ECU or have to repeat the process if the dealership does a update on my vehicle.

[Mr Vegas 540i]

I am still waiting to take possession of my new to me 2021 540i and am brand new to the forum. I’d like to buy a JB+ and a MAD intake from mike@x-ph.com and didn’t know if they offered forum member discounts or whether I should just order from the website?

[Magnit]

Check my numbers from JB+
It is good start.
https://g30.bimmerpost.com/forums/sh....php?t=1991244

[Michaelthomas]

100% worth it. I am running map 2. Xhp stage 2. Little E. Just cranked a 3.1 on a positive slope. Draggy verified.

Compliment it with xhp for sure. There’s a ton of potential.

2023 m550.

[mike@x-ph.com]

Originally Posted by Michaelthomas

100% worth it. I am running map 2. Xhp stage 2. Little E. Just cranked a 3.1 on a positive slope. Draggy verified.

Compliment it with xhp for sure. There’s a ton of potential.

2023 m550.

agree.

if you want more power without sending your DME to Finland, the JB4 is an excellent option

[DarthBMR]

Originally Posted by Mr Vegas 540i

I am still waiting to take possession of my new to me 2021 540i and am brand new to the forum. I’d like to buy a JB+ and a MAD intake from mike@x-ph.com and didn’t know if they offered forum member discounts or whether I should just order from the website?

I have the same car and same exact set up! LOVE IT!! Install on both was easy and the sound/power increase is fantastic!! I really can't image what a BM3 would be like. If you want to keep cost low and really open up the car this is a good combo! I run map 3 on 93 octane.

[Mr Vegas 540i]

Went a little bit different way. Found a JB4 with Bluetooth for $340 locally. And then found a barely used BMS intake locally for $120.

Running tune 3 on 93 makes the car really fun. I get more intake noise but it isn’t noisy at all. I wired the valve in the exhaust open as well and it’s still not very loud, which is fine. I need to put the clip back on and open it now that I have Bimmerlink and pull the fuse.

[ezaircon4jc]

Is it worth it with the availability of only 91 octane?

[mike@x-ph.com]

Originally Posted by ezaircon4jc

Is it worth it with the availability of only 91 octane?

It is , you will still got a noticeable power increase

[SundaySnores]

Originally Posted by Mr Vegas 540i

Went a little bit different way. Found a JB4 with Bluetooth for $340 locally. And then found a barely used BMS intake locally for $120.

Running tune 3 on 93 makes the car really fun. I get more intake noise but it isn’t noisy at all. I wired the valve in the exhaust open as well and it’s still not very loud, which is fine. I need to put the clip back on and open it now that I have Bimmerlink and pull the fuse.

Just getting a JB4. I run 93 fuel all the time, am I able to run that map all the time?

[Mr Vegas 540i]

Originally Posted by SundaySnores

Just getting a JB4. I run 93 fuel all the time, am I able to run that map all the time?

I have been switching between Map 2 and Map 3 just like switching between comfort and sport. Map 2 feels much better than stock and Map 3 is spicier still. You should be able to run it in Map 3 all the time though.

[SundaySnores]

Originally Posted by Mr Vegas 540i

I have been switching between Map 2 and Map 3 just like switching between comfort and sport. Map 2 feels much better than stock and Map 3 is spicier still. You should be able to run it in Map 3 all the time though.

Thanks!

[Trashmanfrank]

Originally Posted by gtazu

My warranty runs out in a couple weeks and I'm interested in maybe tuning my 2021 BMW 540i. Originally I was going to go the Femto and BM3 route but I really don't want to spend $1,500 since I'm starting college in the fall. Is a used JB4 from facebook marketplace worth it, or should I wait for the unlock and BM3 tune?

Send the DME to femto and do a real tune. JB4 is great don’t get me wrong, but a real tune is a night and day difference