Active Autowerke F8x BMW M2C / M3 / M4 Downpipes w GESI G-Sport Cats

[mike@x-ph.com]

Here are dynos showing AA downpipes making more power than stock

[Bettertomorrow]

Thanks for info!

Am I reading the first dyno right?
Stock Tune, GESI Cats, Equal Length MP, Mad Max Rear Muffler
Stock Tune, Stock Cats, Equal Length MP, Stock Rear Muffler

If I am reading it right, GESI Cats with aftermarket muffler
17+ WHP
4+ LB-FT
Assuming I am reading it wrong, and both had stock mufflers, over stock cat, GESI resulted 17+ WHP & 4+ LB-FT.

So, AA Single Mid Pipe advertises the following over stock Mid-Pipe.
18+ WHP over stock*
30+ LB-FT over stock*

My question remains...
Someone with stock DP, Single Mid-Pipe would flow similar/better than
Someone with GESI DP, stock Mid-Pipe?

[mike@x-ph.com]

I dont know which flows better the midpipe or the downpipe, from the dynos i have seen its very similar. If you want more power, you should upgrade both

[hellokitty]

Originally Posted by Bettertomorrow

I've been contemplating DP options (want to go stage 2 or 2+ and call it a day). From my search (correct me if I am wrong), AA GESI downpipe has 400 cell. And stock downpipe also has 400 cell, and this is probably why there would be no CEL.

So the obvious question is this. Putting potentially different material aside, 400 cell per square inch is, 400 cell per square inch, physical barrier does not change. Does $3000 AA GESI flow so much better than stock?

Another question is this. AA Single Midpipe advertises 18+ WHP over stock & 30+ LB-FT over stock (when paired with exhaust, although I think it is marketing, stock exhaust flows just fine, just doesn't sound great). If single MP is free flowing as the following video, is stock downpipe good enough for Stage 2 or Stage 2+ with Single MP? (I asked MHD and MHD told me to use Stage 1, appreciated their candid response).

So here is what I gather so far.
Stage 2 or Stage 2+ would benefit from DP if DP is 200 cell or straight. But there is no proven & convenient way to work around emission (other than reverting to stock DP, stock tune, so forth).

Stock DP probably flows similar to AA GESI DP. Meaning I could get AA GESI. run Stage 2, and be able to say, "I am stage 2 with DP"! But the performance may be similar to running Stage 2 with stock DP.

Single MP is freer flowing (perhaps in the realm of having 200 cell DP with stock MP?), could support Stage 2, and still keep emission happy as long as I don't disable 2nd O2s. (I think I am emission ready with Stage 1 according to MHD scan).

Stock DPs are rated for stock power. Once you go beyond that, stock DPs are a bottle neck. Big HP factory cars like Hellcats must use hardware rated for its power levels while being able to pass emissions. That is where AA w/GESI comes in. You are putting in a bigger diameter cat to be able to flow more than a factory DP despite both being 400 cell sq/in.

[TR930]

Originally Posted by Bettertomorrow

Thanks for info!

Am I reading the first dyno right?
Stock Tune, GESI Cats, Equal Length MP, Mad Max Rear Muffler
Stock Tune, Stock Cats, Equal Length MP, Stock Rear Muffler

If I am reading it right, GESI Cats with aftermarket muffler
17+ WHP
4+ LB-FT
Assuming I am reading it wrong, and both had stock mufflers, over stock cat, GESI resulted 17+ WHP & 4+ LB-FT.

So, AA Single Mid Pipe advertises the following over stock Mid-Pipe.
18+ WHP over stock*
30+ LB-FT over stock*

My question remains...
Someone with stock DP, Single Mid-Pipe would flow similar/better than
Someone with GESI DP, stock Mid-Pipe?

Either upgrade in mid pipe or down pipe over stock should be an improvement.
The stock midpipe has secondary cats in them, the AA midpipe does not, so it should flow better ( and prob better than the EL AA midpipe TBH).

No one is going to be able to definitively answer your question though unless they have the mods on the same car, same conditions, on a dyno.

If you can only afford one, I would do the midpipe since it removes secondary Cats
I will run both GESI cats and Single midpipe.

[Bettertomorrow]

Originally Posted by hellokitty

Stock DPs are rated for stock power. Once you go beyond that, stock DPs are a bottle neck. Big HP factory cars like Hellcats must use hardware rated for its power levels while being able to pass emissions. That is where AA w/GESI comes in. You are putting in a bigger diameter cat to be able to flow more than a factory DP despite both being 400 cell sq/in.

Thank you all for info, very informative!

Stock DP must be rated higher than stock power? GTS has the same cat as civil M4? And there is close to 100 hp difference?

I guess my question stems from MHD recommending Stage 1 for a car that has single mid pipe when overall flow would be the same or even better than aftermarket DP & stock MP.

I might just end up getting GESI, just want to know if it will be money well spent other than being able to say I got DP vs stock DP. It looks like it is backordered from AA but Turner seems to have it stock.

[hellokitty]

Originally Posted by Bettertomorrow

Thank you all for info, very informative!

Stock DP must be rated higher than stock power? GTS has the same cat as civil M4? And there is close to 100 hp difference?

I guess my question stems from MHD recommending Stage 1 for a car that has single mid pipe when overall flow would be the same or even better than aftermarket DP & stock MP.

I might just end up getting GESI, just want to know if it will be money well spent other than being able to say I got DP vs stock DP. It looks like it is backordered from AA but Turner seems to have it stock.

You should order from extreme powerhouse. Mike can get it to you quick. These are built to order so it will take about 2 weeks to arrive at your door step.

[mike@x-ph.com]

Originally Posted by hellokitty

You should order from extreme powerhouse. Mike can get it to you quick. These are built to order so it will take about 2 weeks to arrive at your door step.

We have a few sets built and ready to ship, no need to wait 2 weeks anymore

[TR930]

Mine are finally going in with a turbo upgrade next week. AA catted to AA Single Mid to Dinan rear Muffler.

[mike@x-ph.com]

Originally Posted by TR930

Mine are finally going in with a turbo upgrade next week. AA catted to AA Single Mid to Dinan rear Muffler.

Nice!! Looking forward for your feedback

[JAI///M3]

Originally Posted by TR930

Mine are finally going in with a turbo upgrade next week. AA catted to AA Single Mid to Dinan rear Muffler.

Sounds like an awesome build. Post some sounds clips if ya can!!

[TR930]

Just got the car back. Sound is VERY close to OEM but seems "smoother". There is zero rasp, zero drone. Hard to know if it actually flows better since I had turbos put in so obviously the car is faster up top. Very refined, no weird rattles or vibrations with the AA midpipe and Dinan. It gets louder up top but again no rasp or drone. No smell at all, no CEL. Very pleased so far. I'll report back on cold start in the am.

Oh, I turned off burbles and the sound of the car was just so smooth. I checked my OEM cats too since I had burbles on and they appeared fine. I was running BM3 OTS stage 2. Now I'm on 2H91 OTS with a custom tune going in next week.

[mike@x-ph.com]

Originally Posted by TR930

Just got the car back. Sound is very close to OEM but seems "smoother". There is zero rasp, zero drone. Hard to know if it actually flows better since I had turbos put in so obviously the car is faster up top. Very refined, no weird rattles or vibrations with the AA midpipe and Dinan. It gets louder up top but again no rasp or drone. No smell at all, no CEL. Very pleased so far. I'll report back on cold start in the am.

Oh, I turned off burbles and the sound of the car was just so smooth. I checked my OEM cats too since I had bubbles on and they appeared fine. I was running BM3 OTS stage 2. Now I'm on 2H91 OTS with a custom tune going in next week.

[TR930]

Cold start was exactly the same as OEM.
I'm struck by how smooth the sound is now, not a hint of rasp, farts or anything. Even with flaps open. It sounds "clean" if that makes any sense. Again my burbles are OFF.

[Wtfitzvi]

Has anyone have any issues passing NYS inspection with these downpipes? Currently have remus axle back and AA single mid pipe. Justing missing downpipes so I can go to stage 2. I just don't want to deal with the hassle of failing state inspection due to monitor issues.

[RobDee]

Originally Posted by hellokitty

Someone dyno these bad boys

I wonder how they will hold up to full E85 boost levels.

Would be nice to have a catted option to minimize rasp and smell.

I'd like to see that too!!

[RobDee]

anyone install these yet? if so, whats the verdict?

[hellokitty]

Originally Posted by RobDee

anyone install these yet? if so, whats the verdict?

- Quieter than catless but not by much

- No check engine light. It's been about 10,000 miles. , no issues.

- Deep sound, no rasp

- Doesn't feel like I lost any power. I'm on full E85 stage 2 Cary Jordan tune.

- Fit and finish as you would expect. Just like OEM.

[mike@x-ph.com]

Originally Posted by hellokitty

- Quieter than catless but not by much

- No check engine light. It's been about 10,000 miles. , no issues.

- Deep sound, no rasp

- Doesn't feel like I lost any power. I'm on full E85 stage 2 Cary Jordan tune.

- Fit and finish as you would expect. Just like OEM.

[RobDee]

Originally Posted by hellokitty

- Quieter than catless but not by much

- No check engine light. It's been about 10,000 miles. , no issues.

- Deep sound, no rasp

- Doesn't feel like I lost any power. I'm on full E85 stage 2 Cary Jordan tune.

- Fit and finish as you would expect. Just like OEM.

have you done mid-pipe/pipes and or rear exhaust? just got my car and still trying to figure out whats working best for everyone

[mike@x-ph.com]

Originally Posted by RobDee

have you done mid-pipe/pipes and or rear exhaust? just got my car and still trying to figure out whats working best for everyone

I tried a few different setups, and the best one in my opinion is the catted downpipe + resonated equal length + Remus axle back

[CruzM3]

Originally Posted by mike@x-ph.com

I tried a few different setups, and the best one in my opinion is the catted downpipe + resonated equal length + Remus axle back

I think I'll be doing something similar with my AA catted downpipes. Right now they are matted to the stock system but I'm planning to add AA single mid and Remus muffler.