[badseedtech]

2022 540i, still under manu warranty until Feb 2026, CPO warranty until Feb ‘27.

Tues I’m doing MAD intake, inlet, axle-back, exhaust flap controller, and a Remus midpipe. I have no current plans to do even a high-flow catted downpipe bc I’m not interested in the car (even faintly) smelling like fuel.

Question is…JB4 or full send it w Femto and BM3? Cost/wait time isn’t the issue.

Main question is whether its even worth going Femto/BM3 and definitely voiding my warranty vs JB4 and only possibly voiding my warranty if I’m not planning on a downpipe.

Main hesitation with the JB4 is I don’t want it to sound too obnoxious and BM3 has burble control - and I hear throttle reaponse is smoother.

[badseedtech]

Alternately, talk me *into* a AA catted downpipe lol

[drive_to_survive]

ahem, so 2021 540i here.
Ran a racechip and AA catted downpipe for 7-8 months.

While the initial power bump was nice (especially adding 2 gallons of ethanol to smooth out the car on map 7 of racechip), its nothing compared to a proper tune.

With CPO still remaining, finally decided to buckle up and send the ECU for femto.
Bought the MHD and XHP license, installed the MHD flexfuel kit.

I still remember the initial first pull after the flash.
I was shouting holly fuck in my head with a big grin.

I would acutally push you to go for femto unlock and enjoy your car like you bought something 1 level up.

[badseedtech]

Originally Posted by drive_to_survive

ahem, so 2021 540i here.
Ran a racechip and AA catted downpipe for 7-8 months.

While the initial power bump was nice (especially adding 2 gallons of ethanol to smooth out the car on map 7 of racechip), its nothing compared to a proper tune.

With CPO still remaining, finally decided to buckle up and send the ECU for femto.
Bought the MHD and XHP license, installed the MHD flexfuel kit.

I still remember the initial first pull after the flash.
I was shouting holly fuck in my head with a big grin.

I would acutally push you to go for femto unlock and enjoy your car like you bought something 1 level up.

Dude, this is gold. I appreciate you taking the time. I’m so close to just pulling the DME.

How is the smell w the AA? Did you go Active or GESY cat?

[drive_to_survive]

Originally Posted by badseedtech

Dude, this is gold. I appreciate you taking the time. I’m so close to just pulling the DME.

How is the smell w the AA? Did you go Active or GESY cat?

I think AA does a pretty good job of giving you a stock Cat experience (only in terms of smell, the turbo sounds are definitely there )

Never smelled anything in the cabin even during long traffic stops, even with the windows open.

Only time you smell something slightly is when you start the car in a closed garage but that too is barely irritating.

As for the warranty claims, if your service advisor is pretty cool with tunes, your should have no issues.
I have had a warranty work done on my car even after the tune and the SA aware of it.

Since it was unrelated to the engine they were cool with it.

EDIT: I bought it when there weren't two options. So I am guessing I am on GESY. (the more expensive one I assume)
I did drive a catless M5 and the smell was horrible.
So, I share the same preference as you about the smell and would never go for a catless one.
AA is more expensive but totally worh it.

[badseedtech]

Originally Posted by drive_to_survive

I think AA does a pretty good job of giving you a stock Cat experience (only in terms of smell, the turbo sounds are definitely there )

Never smelled anything in the cabin even during long traffic stops, even with the windows open.

Only time you smell something slightly is when you start the car in a closed garage but that too is barely irritating.

As for the warranty claims, if your service advisor is pretty cool with tunes, your should have no issues.
I have had a warranty work done on my car even after the tune and the SA aware of it.

Since it was unrelated to the engine they were cool with it.

EDIT: I bought it when there weren't two options. So I am guessing I am on GESY. (the more expensive one I assume)
I did drive a catless M5 and the smell was horrible.
So, I share the same preference as you about the smell and would never go for a catless one.
AA is more expensive but totally worh it.

Lol shit…I think I’m in. Thank you for contributing to my degeneracy 🫡

[overcooked]

I got femto unlock on both my x7 40i and 540i. Went with mhd and xhp.
The car pulls a lot stronger now while still smooth as silk. I wouldn’t worry about warranty one bit given it’s B58.
Only regret was not doing it sooner.

[badseedtech]

Originally Posted by overcooked

I got femto unlock on both my x7 40i and 540i. Went with mhd and xhp.
The car pulls a lot stronger now while still smooth as silk. I wouldn’t worry about warranty one bit given it’s B58.
Only regret was not doing it sooner.

Nice. You do a down pipe?

[overcooked]

Originally Posted by badseedtech

Nice. You do a down pipe?

No, I am satisfied with the power, and I got an e85 station nearby if I wanted to tap into more power. It’s my daily so didn’t plan to go too crazy.

[Tpriest7893]

I bought my 2020 with 30k miles currently at 57k.. using a jb+ until my warranty runs out. I’m on bmw warranty. I wouldn’t flash if you have a bmw warranty.
My buddy had a 3rd party warranty and got like 8k of work done on his car and they could care less about the warranty. The b58 is more reliable but shit happens. Already had my oil pan gasket leak fixed under warranty. My car was giving me low oil signs
And boom. Knock on wood wveydbting else been great

[drive_to_survive]

Originally Posted by Tpriest7893

I bought my 2020 with 30k miles currently at 57k.. using a jb+ until my warranty runs out. I’m on bmw warranty. I wouldn’t flash if you have a bmw warranty.
My buddy had a 3rd party warranty and got like 8k of work done on his car and they could care less about the warranty. The b58 is more reliable but shit happens. Already had my oil pan gasket leak fixed under warranty. My car was giving me low oil signs
And boom. Knock on wood wveydbting else been great

God forbid but if you need to make a claim against an engine work, even the JB4 install can be detected as your logs would have out of range boost values and might be a problem for the claim. (even if it was taken out before bringing in the car)

Depends on how big of a work the claim is, how deeply they want to look into it and how friendly the dealer/service advisor is.
Yes, a flash tune will mostly flag your car once connected to ISTA. (mostly as mine was not flagged last time when my SA had to connected it for a brake pad replacement, surprising)

Given how reliable B58s have been, I feel its worth taking the risk. Had it been the N63 in context, I would have advised otherwise.

[Tpriest7893]

Originally Posted by drive_to_survive

God forbid but if you need to make a claim against an engine work, even the JB4 install can be detected as your logs would have out of range boost values and might be a problem for the claim. (even if it was taken out before bringing in the car)

Depends on how big of a work the claim is, how deeply they want to look into it and how friendly the dealer/service advisor is.
Yes, a flash tune will mostly flag your car once connected to ISTA. (mostly as mine was not flagged last time when my SA had to connected it for a brake pad replacement, surprising)

Given how reliable B58s have been, I feel its worth taking the risk. Had it been the N63 in context, I would have advised otherwise.

For sure. I asked my bmw tech and they told me don’t flash. They said a jb4 was fine, I still unplug it when I go in just incase

[Trashmanfrank]

1000% send it to femto. I did everything myself, ie ordering and shipping directly through femto. From the day I dropped it off at DHL I had my DME back 5 days later.

I ran a JB4 for years and loved it at the time, when I went to a full custom tune it was night and day.

Warranty is voided regardless of what people say, I had a dealer flag me for “tune” even with a JB4 uninstalled. They can only refuse the work if they can prove the tune directly effected the part.

AA catted downpipe is great, I had one on my 540… it’s pricey for what it is. I run a MAD 200 cel downpipe now and just disable the codes in the tune. Very little smell on E50.

[badseedtech]

Originally Posted by Trashmanfrank

1000% send it to femto. I did everything myself, ie ordering and shipping directly through femto. From the day I dropped it off at DHL I had my DME back 5 days later.

I ran a JB4 for years and loved it at the time, when I went to a full custom tune it was night and day.

Warranty is voided regardless of what people say, I had a dealer flag me for “tune” even with a JB4 uninstalled. They can only refuse the work if they can prove the tune directly effected the part.

AA catted downpipe is great, I had one on my 540… it’s pricey for what it is. I run a MAD 200 cel downpipe now and just disable the codes in the tune. Very little smell on E50.

Yo thanks, I appreciate the input. I’m gonna full send it and pay to play if something breaks. I’ve had quite a few people tell me the JB4 was ok until they experienced a proper tune so I think I’ll just skip that step.

Probably have to stick with AA even w the cost bc its hard to find e85 here. Closest is like 45 min.

[Trashmanfrank]

Originally Posted by badseedtech

Yo thanks, I appreciate the input. I’m gonna full send it and pay to play if something breaks. I’ve had quite a few people tell me the JB4 was ok until they experienced a proper tune so I think I’ll just skip that step.

Probably have to stick with AA even w the cost bc its hard to find e85 here. Closest is like 45 min.

AA makes a great downpipe, but… if you are going to disable the CEL anyways, any 300-400 cell catted downpipe will do. Alibaba has been crushing it lately with downpipes 🤣

https://www.alibaba.com/x/B0403L?ck=pdp