[jmac2224]

Im thinking about adding a jb4 and a downpipe and maybe a full exhaust to my m340i and im wondering if i need a full flash tune to get the benefits of the downpipe.

also wondering if adding those will void my warranty as the car is still new.

[mike@x-ph.com]

There is no need for the flash tune, but you need a downpipe that does not trigger the check engine light since the JB4 will not hide the code.

I recommend the active autowerke downpipe

[Basterma]

will jb4 work on a 2023 m340i?

[RTPenland]

Originally Posted by Basterma

will jb4 work on a 2023 m340i?

JB4 works on just about any model car with a turbo - hell if a lawnmover had a turbo they'd probably offer a JB4 for that too. Is it as good as a flash, no, is it a good alternative if your only other option is to send your dme overseas for an unlock and subsequent flash yes.

[mike@x-ph.com]

Originally Posted by RTPenland

JB4 works on just about any model car with a turbo - hell if a lawnmover had a turbo they'd probably offer a JB4 for that too. Is it as good as a flash, no, is it a good alternative if your only other option is to send your dme overseas for an unlock and subsequent flash yes.

funny and probably true

[PaymentNinja]

Originally Posted by jmac2224

Im thinking about adding a jb4 and a downpipe and maybe a full exhaust to my m340i and im wondering if i need a full flash tune to get the benefits of the downpipe.

also wondering if adding those will void my warranty as the car is still new.

When I installed JB4 I did catted downpipe from ApexBuilt, left exhaust stock. You’ll get good sound and performance out of the DP and JB4. Save the money on the exhaust for something else IMO.

[mike@x-ph.com]

Originally Posted by PaymentNinja

When I installed JB4 I did catted downpipe from ApexBuilt, left exhaust stock. You’ll get good sound and performance out of the DP and JB4. Save the money on the exhaust for something else IMO.

tune + downpipe is the most popular starting combo

if you want more sound, the exhaust mod is a must.

[Randy Johnson]

Does a JB4 actually work? IE increase hp/tq? I've read a lot of post stating after install users saw no improvement in 0-60 and 1/4 mile times. Wonder if it will produce codes.

[mike@x-ph.com]

Originally Posted by Randy Johnson

Does a JB4 actually work? IE increase hp/tq? I've read a lot of post stating after install users saw no improvement in 0-60 and 1/4 mile times. Wonder if it will produce codes.

The Jb4 adds a boost, which creates more power.

2 reasons why sometimes more boosts do not lead to power; the first reason is traction control. So you might notice the car a lot faster on the highway than from a full stop.

the second reason is that your map is too aggressive for your fuel causing your DME to drop ignition timing which leads to a loss of power

[komoornik]

Originally Posted by Randy Johnson

Does a JB4 actually work? IE increase hp/tq? I've read a lot of post stating after install users saw no improvement in 0-60 and 1/4 mile times. Wonder if it will produce codes.

Got JB4 as it seems the best option besides the DME unlock and a proper tune.

I of course verified it on the dyno.

Turned out I can pretty much run Map1 (despite using 98 octane EU).

I must say there's not much added top end - ~17HP and 40Nm.

But there's quite some more (30-40HP and up to 50Nm) all the way from 2.4k RPM to redline.

[CarGuy954]

Komoornik is right on the money. There is a little more power to made with some E30 but, it will require a lot of time fine tuning. JB4 will shift your power curve left allowing you to make more torque and Hp sooner. The down fall is its lack of fuel and timing capabilities in the higher rpm. IAT's and Fuel quality play a huge part in keeping it running consistent. If you can pick one up used for less than $400 its less painful, brand new not worth it. You can read on a lot on JB4 tech forums for the struggles and there are a few videos on youtube. The DME unlock and a tune will be the best way to go.

[Randy Johnson]

Originally Posted by komoornik

Got JB4 as it seems the best option besides the DME unlock and a proper tune.

I of course verified it on the dyno.

Turned out I can pretty much run Map1 (despite using 98 octane EU).

I must say there's not much added top end - ~17HP and 40Nm.

But there's quite some more (30-40HP and up to 50Nm) all the way from 2.4k RPM to redline.

Bootmod3 spoiled me on the 435. So easy to tune and the power was amazing. Wish the M340 was this easy. Proving to be a challenge.

[mike@x-ph.com]

Originally Posted by Randy Johnson

Bootmod3 spoiled me on the 435. So easy to tune and the power was amazing. Wish the M340 was this easy. Proving to be a challenge.

the M340 platform is a lot more capable than the 435, just needs a few more upgrades

[Gryph8n]

There is a running post showing M340i draggy times. Take a look at that. I used a JB4 with E35 and downpipe on my M440i and did notice faster 0-60mph and 1/4 mile times, but got a custom tune.