[mike@x-ph.com]

Originally Posted by 340iNL

I went with the Active Autowerke too after debating Akrapovic, HJS, CSG1, AA
I did not want the cheaper ones like VRSF, CTS, etc.

AA and CSG1 are somewhere priced in the middle with no CEL and active autowerke showed some nice support on this forum so I went with them

Friday it will be installed I'll post some vids on the forum

Congrats

[Skyhigh]

Some of you requested updates and more info. Here it is, after some 100km driven today, from relaxed cruising to 0-100 runs

- There is a metallic element in the sound in idle. Only noticeable from outside though. Reminds me of the metallic echo catless cars produce.
- The sound/noise in Comfort (from the inside) is maybe 5% increased. A bit more drone around 2000 rpm. What is more noticeable is that the sound is now deeper and more masculine Generally though - no effect on the level of comfort when one is just traveling and not up for noise. That is brilliant!
- In Sport / Sport+, the sound is appreciably louder, pronounced and more masculine. Heavy drone around 2000... somewhat annoying. Quite loud in general, both from the inside and outside. For my taste - just on the borderline of what is tolerable. I love the fact that the car has 2 identities with Comfort vs Sport. I wouldn't want this loud if that was permanent and no Comfort mode existed.
Once the ears get used to it, it facilitates the overall sporty feeling and adrenaline I enjoyed that. But be aware - people do turn around.... it draws (sometimes unnecessary) attention.

Based on the above, I for one would not go for 200 cell or catless DP!! Not with an MPPSK exhaust at least. With the Akrapovic and 300HJS cat it reached the maximum tolerable sound/noise level for my liking in Sport and is perfectly fine in Comfort!

Now.... - Performance...
I have done maybe around 15 0-100 runs in the past, all on the same road. I therefore have a solid basis for comparison. It must be said though that the temperature now was approx 7-8 degrees (C) lower, but I don't think this would make that of a huge difference.

My previous best 0-100 kmh with dragy was 4,75 s (corrected for 0,00 slope). I have reached that result only once, whereas most of the other runs were 4,80-4,85 s.
(All my runs are with a full tank, including today's)

Today, the best time I got out of 5 runs was 4,56 s 0-100 kmh (corrected for 0,00 slope), whereas 4 out of 5 runs were below 4,7 s (the worst was 4,72)!
Best 0-60 mph - 4,34 s.

I think it is safe to conclude, that with my setup, the Akrapovic DP knocks off 0,2 - 0,25 s from the 0-100 time on its own, no other mods or software!! In my humble opinion this is quite impressive and more than I hoped for and expected!!! What do you guys think?

[mike@x-ph.com]

Nice! thank you for sharing

[rosstin]

At full throttle have you noticed brief hesitation(s) as you accelerate through the gears?

I do with the same setup. Believe it's throttle closure as the ecu reacts to reaching target boost quicker.

Not a daily issue of course and it's nice to have the sound plus crisper throttle response at all other times. But probably means I'll add a real tune to fully unlock the potential at some point.. as well as remove the unsocial cold start!

[Skyhigh]

Please elaborate? When / at what point do you notice those hesitation(s) exactly? Are they easily reproducible?

[rosstin]

Wide Open Throttle, particularly starting from low speeds / low rpm. Someone showed me some logging from their 140i once - less back pressure means you reach boost quicker. That's good in most driving, but I found in some extreme WOT situations it creates the response I mentioned. Its only momentary and you likely wouldn't notice it if you weren't looking for it.

[imperfectluck]

@rosstin Throttle closures are quite noticeable I'd say through the custom BM3 tune revisions I've been through but I suppose it also depends on how quickly it closes and reopens on your setup.

Regarding the unsocial cold start, I'd much prefer to maintain my HJS cats in my Fabspeed DP vs the minute it takes to warm those precious cats on a cold morning. You did pay for top grade cats for a reason.

[Skyhigh]

Originally Posted by rosstin

Wide Open Throttle, particularly starting from low speeds / low rpm. Someone showed me some logging from their 140i once - less back pressure means you reach boost quicker.

That is 100% correct and precisely what one of the main benefits of a sport-cat / catless DP is. I've seen such logs as well.

That's good in most driving, but I found in some extreme WOT situations it creates the response I mentioned. Its only momentary and you likely wouldn't notice it if you weren't looking for it.

I haven't noticed anything like that (yet). I'd think this would be then noticeable in 0-100 runs where WOT is a given, but I haven't. It is not visible on the dragy acceleration graph either. I'd also think, if this phenomena exists, it would be at least as apparent with 200 cell cats and even more perceivable with catless DPs....? I personally have not seen reports about that anywhere. Have you?

I see you are in UK, which means you are RWD - are you sure it is not a traction issue...?

Originally Posted by imperfectluck

Regarding the unsocial cold start, I'd much prefer to maintain my HJS cats in my Fabspeed DP vs the minute it takes to warm those precious cats on a cold morning. You did pay for top grade cats for a reason.

The cold start is not really "maintaining" the cat... it just gets it to become efficient quicker as it needs temperature to enable the catalytic conversion. It's purely an environmental thing.
This said, unlike the OEM cat, which is ceramic, the HJS cat is metallic. One of the properties of the metallic converters is that they get up to working temperature faster.
I am personally not bothered by the cold start (I even like it), but it depends heavily on where you park. If I parked under people's windows, I can see why it could be a concern.

@rosstin
Two related questions:
- I have noticed that the exhaust smell with the HJS has increased/changed a bit with the new DP. Is that your experience as well?
- Do you also have that new metallic echo in the sound, during cold start but also during idle (only perceivable from outside the vehicle)?

[rosstin]

Originally Posted by imperfectluck

@rosstin Throttle closures are quite noticeable I'd say through the custom BM3 tune revisions I've been through but I suppose it also depends on how quickly it closes and reopens on your setup.

Thanks that's good info. I figured an aftermarket tune might smooth it out a bit. I'll likely still do it eventually for the power gains

[rosstin]

Originally Posted by Skyhigh

I see you are in UK, which means you are RWD - are you sure it is not a traction issue...?

Do you mean traction, or traction control?
Can't rule out the latter, the effect is similar.
But for me it happens in Sport+ and I also have an LSD, so makes it less likely perhaps.

In any case on the 140i graphs I saw, throttle closure was evident. And imperfectluck has mentioned it in their logs too.

Stands to reason if the ecu sees target boost is met/exceeded sooner, it has to do something to adjust. It still assumes factory back pressure.

Back to driving, there must be a whole bunch of factors that influence whether you notice the same.. have fun experimenting

[rosstin]

Originally Posted by Skyhigh

@rosstin
Two related questions:
- I have noticed that the exhaust smell with the HJS has increased/changed a bit with the new DP. Is that your experience as well?
- Do you also have that new metallic echo in the sound, during cold start but also during idle (only perceivable from outside the vehicle)?

- Only before the cat is warm, not after.
- Yes cold start is metallic, raspy, loud and high pitched, not in a good way in my view. I don't remember much change during idle, but the DP definitely makes everything sound more purposeful, perhaps idle too. Except for cold start I love how it sounds!

[IMS-340C]

I also noticed this when doing WOT at low RPM.

It's seems with the cats removed the Turbo spool much faster than the ECU anticipating and it closes the throttle which result in what feels like a bog.

At that point in the logs boost spikes to 21-22 psi on stock Turbo then the throttle closure happens to regulate the boost.

Originally Posted by rosstin

Stands to reason if the ecu sees target boost is met/exceeded sooner, it has to do something to adjust. It still assumes factory back pressure.

[aardate]

Originally Posted by Skyhigh

Some of you requested updates and more info. Here it is, after some 100km driven today, from relaxed cruising to 0-100 runs

- There is a metallic element in the sound in idle. Only noticeable from outside though. Reminds me of the metallic echo catless cars produce.
- The sound/noise in Comfort (from the inside) is maybe 5% increased. A bit more drone around 2000 rpm. What is more noticeable is that the sound is now deeper and more masculine Generally though - no effect on the level of comfort when one is just traveling and not up for noise. That is brilliant!
- In Sport / Sport+, the sound is appreciably louder, pronounced and more masculine. Heavy drone around 2000... somewhat annoying. Quite loud in general, both from the inside and outside. For my taste - just on the borderline of what is tolerable. I love the fact that the car has 2 identities with Comfort vs Sport. I wouldn't want this loud if that was permanent and no Comfort mode existed.
Once the ears get used to it, it facilitates the overall sporty feeling and adrenaline I enjoyed that. But be aware - people do turn around.... it draws (sometimes unnecessary) attention.

Based on the above, I for one would not go for 200 cell or catless DP!! Not with an MPPSK exhaust at least. With the Akrapovic and 300HJS cat it reached the maximum tolerable sound/noise level for my liking in Sport and is perfectly fine in Comfort!

Now.... - Performance...
I have done maybe around 15 0-100 runs in the past, all on the same road. I therefore have a solid basis for comparison. It must be said though that the temperature now was approx 7-8 degrees (C) lower, but I don't think this would make that of a huge difference.

My previous best 0-100 kmh with dragy was 4,75 s (corrected for 0,00 slope). I have reached that result only once, whereas most of the other runs were 4,80-4,85 s.
(All my runs are with a full tank, including today's)

Today, the best time I got out of 5 runs was 4,56 s 0-100 kmh (corrected for 0,00 slope), whereas 4 out of 5 runs were below 4,7 s (the worst was 4,72)!
Best 0-60 mph - 4,34 s.

I think it is safe to conclude, that with my setup, the Akrapovic DP knocks off 0,2 - 0,25 s from the 0-100 time on its own, no other mods or software!! In my humble opinion this is quite impressive and more than I hoped for and expected!!! What do you guys think?

Great stuff here, thanks for sharing.
Its just a matter of time before I get a downpipe and leaning towards Akrapovic. I do have the stock exhaust though and wondering if the sound would be too muted even with the Akro DP, the issue with our cars is that they are very well sound deadened and might get too loud on the outside without even feeling it inside!

[Skyhigh]

There will definitely be a serious difference with the stock exhaust in comparison to the MPPSK exhaust.
As you probably know, the stock exhaust has 2 mufflers on the way even in Sport Mode, whereas the MPPSK is a straight pipe in Sport mode....

This said, you will certainly still get an appreciable sound improvement/increase.

And yes - you are correct, outside is much louder

[aardate]

Originally Posted by Skyhigh

There will definitely be a serious difference with the stock exhaust in comparison to the MPPSK exhaust.
As you probably know, the stock exhaust has 2 mufflers on the way even in Sport Mode, whereas the MPPSK is a straight pipe in Sport mode....

This said, you will certainly still get an appreciable sound improvement/increase.

And yes - you are correct, outside is much louder

I did not know that the MPE is a straight pipe in sport mode! that explains alot!
Either way, I'm going to start with the Akro DP and later on when a catback exhaust mod is due I would have to make a decision whether to do the MPPSK or go with the Akro catback.

[Skyhigh]

Both are very good options. I dislike the Akro tips but that's a luxury problem.
Be careful not to use the MPE abbreviation as that's a different product - an axle-back exhaust (M Performance Exhaust). Whereas the MPPSK is cat-back and effectively, as mentioned - a straight pipe in Sport. This said - I am very happy that it is NOT a straight pipe in Comfort - the noise, in combination with a DP, would be unbearable for cruising. For my liking at least and I am sure for my neighbours and traffic police

[aardate]

Originally Posted by Skyhigh

Both are very good options. I dislike the Akro tips but that's a luxury problem.
Be careful not to use the MPE abbreviation as that's a different product - an axle-back exhaust (M Performance Exhaust). Whereas the MPPSK is cat-back and effectively, as mentioned - a straight pipe in Sport. This said - I am very happy that it is NOT a straight pipe in Comfort - the noise, in combination with a DP, would be unbearable for cruising. For my liking at least and I am sure for my neighbours and traffic police

I am assuming disabling the ASD is a must for this type of exhaust/mod/upgrade?

[Skyhigh]

I would say so. I disabled it even before that, as I hate fake BS. Even with the stock exhaust, the B58 sounds much better and more authentic without ASD. But others disabled it after MPPSK to get rid of annoying drone.

[MTWO]

Man I love everything from Akrapovic but its so much $$ sounds great, not much difference than others in sound department but its top quality of course, OEM

[aardate]

I just ordered the Akrapovic catted downpipe and will be installing it on my stock 340i. I don’t have the mppsk so it will be interesting to see what kind of benefits the DP alone will have in terms of performance and/or sound.
Shoutout to Skyhigh for his great insights, and Mike from x-ph for hooking me up.

[Foriegnmonkey1]

Originally Posted by Skyhigh

I know there are a number of DP threads, but I am specifically interested in the user experience from the Akrapovic DP for B58

- Sound (Start-up; Comfort; Sport)
- Quality in general
- Performance benefits

Yo! I did this one my 340i
Akropovic downpipe with the MPPSK running stage 2 with some e85 mix

It is a Beauty bro, and definitely worth the price tag.
No CEL, no smell, it has the refined quality sound you're looking for

There is nothing better than it.

100% worth it if you have the dough.

Let me know your Twitter I can send over some videos on the sound.

[rlmesq]

I just checked on Amazon shopping. Looks like it's selling for around $1700 USD.

Unfortunately, it's not CARB (California Air Resources Board) approved, despite meeting the more stringent EURO-6 standard, so I might have trouble finding a vendor who will ship to me.