M4 downpipe and Midpipe Upgrades while remaining emissions compliant

[M4Ops]

I'm getting ready to replace the OEM downpipes and mid-pipes on my M4. Currently I have a Borla ATAK exhaust on my car and love it. While trying to balance remaining emissions compliant with performance upgrades, I'd like to get some feedback on downpipes (Cat vs Catted) and double to single mid pip upgrades (VRSF mid pipe).

First question off hand; are those just resonators or cats coming off the OEM mid pipes?

Lastly, anyone have experience with making these upgrades, while remaining emissions compliant?

I'm looking at VRSF high flow mid-pipe kit and the ARM Motorsports Catted Downpipes | BMW F82 M3/M4.

Any constructive input on this would be much appreciated!

[hellokitty]

As far as I am aware, the only 49 state EPA approved downpipe is made by AA with GESI cats. Other catted downpipes will not get o2 ready and therefore not emissions compliant.

[M4Ops]

hellokitty what are your thoughts on keeping OEM down pipes and just swapping out mid pipes for the time being? Really not wanting to drop $3k on emissions compliant downpipes if those are the only ones 49 state legal.

[hellokitty]

Originally Posted by M4Ops

hellokitty what are your thoughts on keeping OEM down pipes and just swapping out mid pipes for the time being? Really not wanting to drop $3k on emissions compliant downpipes if those are the only ones 49 state legal.

Sounds like a plan to me... I would probably go with equal length midpipes or a single midpipe

[TopJimmy]

As Kitty said, only the $$$ cats will pass emissions inspection and not throw a CEL. All sport cats and resonated DPs throw the CEL. Nobody likes to swap pipes annually, twice.

Stock cats flow pretty darn good. They're big 400cpi and are only restrictive on the top end. For your needs keep em on.

A 2-into-1 mid like AA or VRSF helps open up flow a little, but it's mostly sound you get…with a few HP. I like the sound, plus a little low end torque since the DPs can dump pressure a little faster into the big midpipe.

Most rear end exhaust are straight-through when valves are open. If the Borla sounds good with valves closed for early AM driving, and also good when opened up, then I'd keep the Borla rear if I could. Otherwise I'd get a typical small-can rear like Dinan/Remus/Turner.

If you like deep and loud rumble look into the AA Signature full 3.5in single kit. That's my absolute favorite.

[mike@x-ph.com]

I recommend the Active Autowerke downpipe with the GESI cats.

Im not an expert on your state's emission testing but some states don't check the midpipes.

If your state does not i recommend the Active Autowerke or MAD single midpipe

[Info@mad-us.com]

Originally Posted by M4Ops

I'm getting ready to replace the OEM downpipes and mid-pipes on my M4. Currently I have a Borla ATAK exhaust on my car and love it. While trying to balance remaining emissions compliant with performance upgrades, I'd like to get some feedback on downpipes (Cat vs Catted) and double to single mid pip upgrades (VRSF mid pipe).

First question off hand; are those just resonators or cats coming off the OEM mid pipes?

Lastly, anyone have experience with making these upgrades, while remaining emissions compliant?

I'm looking at VRSF high flow mid-pipe kit and the ARM Motorsports Catted Downpipes | BMW F82 M3/M4.

Any constructive input on this would be much appreciated!

Op,

We have the single mid pipe instock and it's not a 3 piece like others being sold.


https://mad-us.com/mad-bmw-f8x-m3-m4...race-included/

We also have catless downpipes which are just as emissions compliant as the non epa compliant catted downpipes you have mentioned.