[CigarManNY]

Hello all - I purchased a '21 M2C which came with an AA non resonated single midpipe. When in sport or sport+ and upshifting, there is that single loud raspy pop during throttle lift in lower (2500-4000) RPM.

(I am not referring to the burbles, I tuned that out with bimmerlink)

Any idea how to tone this down? I was thinking about buying the resonated connecting pipes. Does anyone think that might help? Any suggestions otherwise? I didn't want to do any BM3 or ECU tuning and I don't want to drive it in comfort lol!

Thanks

[NCM2C]

Originally Posted by CigarManNY

Hello all - I purchased a '21 M2C which came with an AA non resonated single midpipe. When in sport or sport+ and upshifting, there is that single loud raspy pop during throttle lift in lower (2500-4000) RPM.

(I am not referring to the burbles, I tuned that out with bimmerlink)

Any idea how to tone this down? I was thinking about buying the resonated connecting pipes. Does anyone think that might help? Any suggestions otherwise? I didn't want to do any BM3 or ECU tuning and I don't want to drive it in comfort lol!

Thanks

Are you in a DCT? Pretty sure that's part of the transmission.

[(K)]

Manuals do it too, I don't think there's a way to get rid of it without tuning. One of my favorite features actually.

[CigarManNY]

OP is in a 6MT. I think it's more pronounced because I am rocking the single pipe and not resonated.

[RJT79]

Manuals definitely does it too, except with stock exhausts and pipes, it doesn't get to be a "pop", more like a "oomph".

[CigarManNY]

Originally Posted by RJT79

Manuals definitely does it too, except with stock exhausts and pipes, it doesn't get to be a "pop", more like a "oomph".

Yeah that's what I understand but I don't want to go back to stock.. so I am thinking run resonated connecting pipes to the stock muffler from my AA single midpipe

[ESB]

Is this the brrraaap sound?

[CigarManNY]

Originally Posted by ESB

Is this the brrraaap sound?

Yes, the braap/pop on throttle lift when upshifting

[Bingham]

Ident exhaust set-up. DCT. Same brrrap/pop…on it hard to say 4k and quick let off. I like it…especially arousing in a tunnel or parking garage.

When I give the signal…unleash hell!

[brad65ford]

Dislike that sound too, the more open / free flowing the exhaust the more pronounced. Its it just diverted air going into the exhaust (left over boost)?

[CigarManNY]

Originally Posted by brad65ford

Dislike that sound too, the more open / free flowing the exhaust the more pronounced. Its it just diverted air going into the exhaust (left over boost)?

Yeah good point. To clarify, it's not the "braap" sound on throttle lift but instead the "POP" that happens after the braap sound

[Enabled]

The braaap is fast acting ignition timing pull (fast ignition retard) to force the engine revs down. It isn't there for the sound as much as it is there to perform its function. I guess the leftover pops are just more fuel in the fast decel phase. Only tuning would be able to reduce that. Or just put in a quieter exhaust.

The first time I heard such a sound was with the Ferrari 360 F1 transmission cars on upshift. It's there to drop the rpm fast.

Too bad it doesn't sound like this.

[Rumbloki]

Originally Posted by CigarManNY

Hello all - I purchased a '21 M2C which came with an AA non resonated single midpipe. When in sport or sport+ and upshifting, there is that single loud raspy pop during throttle lift in lower (2500-4000) RPM.

(I am not referring to the burbles, I tuned that out with bimmerlink)

Thanks.
Glad to know I can tune out the burbles and keep the BARK!

[Info@mad-us.com]

You want to remove the anti-lag pop when changing gears?

[Moflow]

My understanding is that it's just leftover boost going through the engine. Our cars do not have a blowoff valve. I think BMW just opens up the valves and lets the pressure wave blow through the cylinders with no added fuel. The pressure wave then hits the exhaust side of the turbo and keeps it spooled.

(Normally, you'd need a blowoff valve as there is pressurized air after the turbo that has nowhere to go when the throttle body is suddenly closed. BOV's vent to atmosphere or back to the intake on the non-pressurized side of the turbo. Without one, that pressurized air would essentially bounce off the throttle body and hit the turbo(s) going the wrong direction, rapidly slowing them down. Which is super bad for them and also kills all boost.)

Unless i'm totally mistaken, that sound is both serving to extend the longevity of the turbos and providing an anti-lag-like effect.

[CigarManNY]

Originally Posted by Info@mad-us.com

You want to remove the anti-lag pop when changing gears?

Ideally yes, however based on your question, it sounds like it would negatively affect the car's performance if I did so?

Basically I have an unresonated AA midpipe, I would be open to adding resonated connecting pipes if that helps decrease the volume of the "pop" but I'm not sure if it would?

[AWFTMFWIN]

Originally Posted by (K)

Manuals do it too, I don't think there's a way to get rid of it without tuning. One of my favorite features actually.

Best is when you go for full first gear pull and upshift in a tunnel or underpass and you're rewarded with a nice gunshot sounding crack

[Info@mad-us.com]

Originally Posted by CigarManNY

Ideally yes, however based on your question, it sounds like it would negatively affect the car's performance if I did so?

Basically I have an unresonated AA midpipe, I would be open to adding resonated connecting pipes if that helps decrease the volume of the "pop" but I'm not sure if it would?

It's part of the software and used to keep the boost up between shifts. Adding resonators will indeed help with the sound level.

[CigarManNY]

Originally Posted by Info@mad-us.com

It's part of the software and used to keep the boost up between shifts. Adding resonators will indeed help with the sound level.

And that gets to the root of my question, thank you greatly.

[Info@mad-us.com]

Originally Posted by CigarManNY

And that gets to the root of my question, thank you greatly.

Welcome!