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2Addicts | BMW 2-Series forum Technical Topics B58 (M240i) Engine, Transmission, Exhaust, Tuning What exhaust for gains ?

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      08-03-2022, 03:34 PM   #1
Edgarm8933
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What exhaust for gains ?

I'm a noob and yes I've read but I'm still confused. Help a brother out.

So I have a 2020 m240ix only mod I have is a dinan midpipe. The car has stock exhaust. Is there any performance gain upgrading the exhaust ? Or is stock fine ? I want it to sound mean but not annoying with all those crazy pops and bangs.

Dinan midpipe sounds fine and I don't want louder burbles than what it does now. More like a meaner growl would sound good.

I want a high flow downpipe eventually to pair with what I already have. I don't mean to sound dumb but does a downpipe replace the midpipe or is it all part of the exhaust ?

Thanks guys
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      08-03-2022, 03:56 PM   #2
marcthedark
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Catback an exhaust will change very little to nothing iro power

The Downpipe connects to the Midpipe which connects to the Axleback (Midpipe + Axelback = Catback)

For power gains you will need to change the downpipe to one with a high-low cat (catless will probably not sound good to you)''

Pops/Bangs/Burbles do not change (beside in volume) when you touch the exhaust. They can be removed or enhanced via ECU tuning (MHD, BM3,....).

If you don't want to go with an ECU tune I would suggest the AA catted downpipe as you won't get a CEL etc.

If you want more power go Stage 2 after adding the Downpipe and add easy power in the 75-100hp range
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      08-03-2022, 07:08 PM   #3
freakystyly
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Quote:
Originally Posted by Edgarm8933 View Post
I don't mean to sound dumb but does a downpipe replace the midpipe or is it all part of the exhaust ?
Not dumb just easy

The downpipe is the pipe coming out of your turbo. It will have 2x O2 sensors connected to it as well as your catalytic converter which is inside the fat part of the pipe.

After the downpipe there's a seam which connects to the mid pipe. That in stock form has a resonator which looks similar to a muffler. It connects to the muffler which is behind the rear axle (axle back).

IMO if you are planning on doing the downpipe, start there and see if you like the sound before other mods.
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      08-03-2022, 07:15 PM   #4
Edgarm8933
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Ok thanks fellas that explains it lol im thinking of getting a bm3 tune but not stage 1 instead a stage 2. Im installing a MST CAI next week.

Next year I'll get a High flow downpipe and then do the stage 2 tune with it. I'll keep the stock exhaust (not M performance) since there's no gains to be had anyways.

It's my daily and I don't track I just drive it hard.
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      08-25-2022, 09:31 PM   #5
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Catback exhaust adding 1/4” of diameter will certainly change things... 3.25 to 3.5” increases something like 20% volumetric efficiency (flow) if I recall correctly. Added to a high flow cat, or catless (better but noisier) creates more flow and quicker spooling. Increasing exhaust (volume) allows you to increase intake with results, nothing works unless you do both. More air in = More air out! Tunes will take advantage of the added air, otherwise gains will be marginal. But from the words of a top tech who races his BMW's, these new ECU's and all the sensors they use can accommodate mechanical changes absent a tune. You won't get what you will with a tune, but the change is still good, the ECU doesn't ignore the increase volume of air... Watch those open cone/Hot Air Induction thingy's, lol, a good high flow filter is all you need. The CAI's are known to cause issues with the maf...

Good Luck!
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      08-28-2022, 01:08 PM   #6
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You do get some performance increase from an exhaust upgrade but it's minimal. If your goal is more power, get a tune, charge pipe, intercooler, downpipe and an intake first
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