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      08-16-2013, 03:22 PM   #1
F12M6MD
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AMS Catted Downpipes - My First Impression...

2013 F13 M6
Meisterschaft full cat-back GTC
AMS catted downpipes
Carbon filter delete

Sound: 50% louder in every way from my GTC sound. Turbo spool very prominent. Rattling from wastegates as engine rests from 2500rpm to idle prominent. Aural pleasure - ridiculous.

Install: 3-4 hours
Size differences: stock pipes are huge, double wrapped heat shielded. AMS slim in comparison. Diameter of stock cats are larger than AMS (maybe compensating for more restrictive stock cats).

Gains: Negligible (~495whp, ~465tq). I was anticipating differences in the 30's. But no.
I did 7 runs on dynojet mixed before and after with ample time for cool down. Went on 20 mile drive and cooled down after install before post-install dyno. I'm just not seeing significant or consistent gains beyond 5hp anywhere in the rev range.

I hope others are getting better results. Look forward to hearing your feedback. I'll post sound, video, dyno when I'm near a computer.

Mark
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      08-16-2013, 03:26 PM   #2
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Mark,
I never dynoed my car but my rear end dyno says big difference in 2nd and 3rd. Again I think a lot has to do with the DME and how it adjusts. then again like you I have a full cat back exhaust, Akra with the x-pipes/etc. Not sure why you are not seeing about a 30hp gain since most are. Give it time let he DME adjust. Also are you running a tune or stock? I kept mine stock but with the latest updates. Supposedly you need a tune to realize the full potential.

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      08-16-2013, 04:08 PM   #3
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I agree with noushy..... you should have driven the car 500-1000 miles before doing a dyno after install. tell me more about the waste gates.. do you hear them all the time even at idle rattling?
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      08-16-2013, 07:03 PM   #4
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Quote:
Originally Posted by noushy View Post
Mark,
I never dynoed my car but my rear end dyno says big difference in 2nd and 3rd. Again I think a lot has to do with the DME and how it adjusts. then again like you I have a full cat back exhaust, Akra with the x-pipes/etc. Not sure why you are not seeing about a 30hp gain since most are. Give it time let he DME adjust. Also are you running a tune or stock? I kept mine stock but with the latest updates. Supposedly you need a tune to realize the full potential.

Noushy
Hey Noushy,

I definitely can "feel" a difference in 2nd and 3rd. I did some urban roads and freeway driving. I didn't really push it entirely yet mostly because I didn't want to scare the sh*t out of people around me. Lol. My tune is stock. My installer (does highly modded porsche turbos, etc) said that in his experience the DME does not need a long time to adapt in full throttle exercises, more so in the long term adaptability in normal driving. I first offered to bring the car back in a week but he convinced me otherwise. Maybe I'll swing back by and re-dyno after a 1000 miles. Thanks for the suggestion. I definitely am waiting for a Dinan tune. Interestingly, we also did before and after clearing codes dynos and I ran similar numbers (despite the car having a reset timing and potentially running rich). What kind of gains did you guys see and where?

Oh one more thing...what updates you speak of? I have not reached my first major service yet (I'm at 10500).

Mark
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Last edited by F12M6MD; 08-16-2013 at 07:17 PM..
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      08-16-2013, 07:13 PM   #5
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Originally Posted by Hunter5179 View Post
I agree with noushy..... you should have driven the car 500-1000 miles before doing a dyno after install. tell me more about the waste gates.. do you hear them all the time even at idle rattling?
Hey Hunter,

Yeah I'll give it some time for sure.
Regarding the rattling, only coming down off revs. Not at idle. Again, my installer (very sharp) noticed that it was occurring as my waste gates were closing (he was visibly able to see this occur). His explanation (as he pulled out an old GT-R turbo) was that the gate does not provide a tight connection necessarily as it closes and it can rattle. The reason he thought it was more than before (I had some rattling after my GTC exhaust) was that the backpressure was now much less which didn't promote a quicker or stronger seal as wastegates were closing. Hmmm. I'm no mechanic. Does this sound plausible? Thanks for your input.

Mark
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      08-16-2013, 07:42 PM   #6
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Quote:
Originally Posted by F12M6MD View Post
Hey Hunter,

Yeah I'll give it some time for sure.
Regarding the rattling, only coming down off revs. Not at idle. Again, my installer (very sharp) noticed that it was occurring as my waste gates were closing (he was visibly able to see this occur). His explanation (as he pulled out an old GT-R turbo) was that the gate does not provide a tight connection necessarily as it closes and it can rattle. The reason he thought it was more than before (I had some rattling after my GTC exhaust) was that the backpressure was now much less which didn't promote a quicker or stronger seal as wastegates were closing. Hmmm. I'm no mechanic. Does this sound plausible? Thanks for your input.

Mark


Yes, that sounds pretty accurate actually. That might be just what it is.... but mine is clearly noticeable at idle also so I'm not sure..in my case.
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      08-16-2013, 10:18 PM   #7
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The gains most are seeing with the downpipes are 30-40hp depending on cats/no-cats. It seems that according to those in the know boost is limited in lower gears and builds in the higher gears, probably why we are feeling it in 2nd and 3rd not so much in 1st. I would bet part of the problem is the DME is limiting boost and thus not seeing bigger dyno gains. I guess track times or quarter mile times might be a better measure.

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      08-17-2013, 10:03 AM   #8
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I just bought my car, no mods yet. What are the typical stock RWHP/Torque? I tried to search for the dyno charts and got a bunch of old threads.
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      08-17-2013, 10:45 PM   #9
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Mark, any sound clips?
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      08-18-2013, 05:12 PM   #10
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Quote:
Originally Posted by greentrbo95gst View Post
Mark, any sound clips?
Hey buddy,

Have not been able to grab any sound clips yet. I do not have a gopro either. I'll try to get you a cold start and some revs with my iphone soon. Coming from the Meisterschaft sound I will tell you the sound is scary, ridiculous loud. If I'm driving around the city, I really feel bad doing any moderate-aggressive accelerating because I fear that people around me would be either super impressed or the opposite. I was at a shop this weekend that tunes GT-R's and they were impressed with the sound.

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      08-18-2013, 07:07 PM   #11
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Quote:
Originally Posted by F12M6MD View Post
Hey buddy,

Have not been able to grab any sound clips yet. I do not have a gopro either. I'll try to get you a cold start and some revs with my iphone soon. Coming from the Meisterschaft sound I will tell you the sound is scary, ridiculous loud. If I'm driving around the city, I really feel bad doing any moderate-aggressive accelerating because I fear that people around me would be either super impressed or the opposite. I was at a shop this weekend that tunes GT-R's and they were impressed with the sound.

Mark
scary and ridiculous sounds good....
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      08-18-2013, 07:17 PM   #12
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Quote:
Originally Posted by noushy
The gains most are seeing with the downpipes are 30-40hp depending on cats/no-cats. It seems that according to those in the know boost is limited in lower gears and builds in the higher gears, probably why we are feeling it in 2nd and 3rd not so much in 1st. I would bet part of the problem is the DME is limiting boost and thus not seeing bigger dyno gains. I guess track times or quarter mile times might be a better measure.

Noushy
My DP have DEFINITELY made a difference in 1st gear. Spins up much faster than my F12. Hard to get the power down. Mine are modified OEM not AMS.
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      08-18-2013, 10:44 PM   #13
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I just installed catted AMS a few days ago with stock exhaust and was feeling a little disappointed as well with power increase. Feels stronger in 2nd/3rd gear but I feel like it might have lost some top end in the 80 to 100 mph range. Hopefully it's just the ECU needing to adjust with some more miles.... I forgot to get it dynoed to see actual increase unfortunately.
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      08-18-2013, 11:05 PM   #14
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Quote:
Originally Posted by delano
I just installed catted AMS a few days ago with stock exhaust and was feeling a little disappointed as well with power increase. Feels stronger in 2nd/3rd gear but I feel like it might have lost some top end in the 80 to 100 mph range. Hopefully it's just the ECU needing to adjust with some more miles.... I forgot to get it dynoed to see actual increase unfortunately.
Hey delano,

Are you getting any rattling noise when you are decelerating or coming down off revs?

Mark
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      08-19-2013, 02:48 AM   #15
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Hey Mark,

No rattles, it sounds pretty good. Especially in the mid to high RPMs.

Michael
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      08-19-2013, 06:48 AM   #16
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Quote:
Originally Posted by F12M6MD
Quote:
Originally Posted by delano
I just installed catted AMS a few days ago with stock exhaust and was feeling a little disappointed as well with power increase. Feels stronger in 2nd/3rd gear but I feel like it might have lost some top end in the 80 to 100 mph range. Hopefully it's just the ECU needing to adjust with some more miles.... I forgot to get it dynoed to see actual increase unfortunately.
Hey delano,

Are you getting any rattling noise when you are decelerating or coming down off revs?

Mark
The rattling you are experiencing are the wastegates. This has been driving Hunter crazy for weeks. I get it at slow speeds especially in a parking lot but I am probably used to it. Feel it has to do with the fact that boost builds so quickly the wastegates rattles when closing because of minimal backpressure.

Noushy
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      08-19-2013, 09:50 AM   #17
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Quote:
Originally Posted by noushy View Post
The rattling you are experiencing are the wastegates. This has been driving Hunter crazy for weeks. I get it at slow speeds especially in a parking lot but I am probably used to it. Feel it has to do with the fact that boost builds so quickly the wastegates rattles when closing because of minimal backpressure.

Noushy
I am just going to throw out there that perhaps you need at least a certain "minimum" level of back pressure form catted pipes to build the boost properly. Mine have 400 cell cats and I experience NONE of this-only more power form low to high end of the revs and a nice increase in exhaust note with ZERO rattles. Basically no negative effects. All very positive benefits.
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      08-19-2013, 09:53 AM   #18
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Quote:
Originally Posted by ColdList
Quote:
Originally Posted by noushy View Post
The rattling you are experiencing are the wastegates. This has been driving Hunter crazy for weeks. I get it at slow speeds especially in a parking lot but I am probably used to it. Feel it has to do with the fact that boost builds so quickly the wastegates rattles when closing because of minimal backpressure.

Noushy
I am just going to throw out there that perhaps you need at least a certain "minimum" level of back pressure form catted pipes to build the boost properly. Mine have 400 cell cats and I experience NONE of this-only more power form low to high end of the revs and a nice increase in exhaust note with ZERO rattles. Basically no negative effects. All very positive benefits.
Interesting that was my thought. AMS went with 300 cell instead of the 200 cell Porsche, Nismo and others use. I suspect the 400 is better with less rattling and more stock sound but a slight bit more restriction. I wish we had a choice between 200-400 as now knowing what I do I would have chosen 400 for a little less noise, smell and rattling. I do get a bit of smell at startup until the cats heat up which I suspect the larger cell size takes more time.

Noushy
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      08-19-2013, 10:14 AM   #19
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Quote:
Originally Posted by F12M6MD View Post
Hey delano,

Are you getting any rattling noise when you are decelerating or coming down off revs?

Mark
I posted this in another thread...I know, agree and hear everything you are describing.. mine does it even at idle too, it's very annoying. If it didn't do it at idle I would be Ok with it. Others don't hear it as much.. mine happens to be on the loud side. It's a total buzz kill because it sounds like the car has a loose exhaust or something. Mine is currently at the dealer.. its Def the wastegates but I don't know how it could be minimized... maybe possibly replace the waste gates?? I love the sound and benefits of the DP's but the wastegates have to be addressed somehow because I definitely don't want to have to remove my DP's because I like them a lot. I am also baffled as to why some hear it louder than others.
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      08-19-2013, 10:50 AM   #20
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Quote:
Originally Posted by noushy View Post
Interesting that was my thought. AMS went with 300 cell instead of the 200 cell Porsche, Nismo and others use. I suspect the 400 is better with less rattling and more stock sound but a slight bit more restriction. I wish we had a choice between 200-400 as now knowing what I do I would have chosen 400 for a little less noise, smell and rattling. I do get a bit of smell at startup until the cats heat up which I suspect the larger cell size takes more time.

Noushy
Smell? ZERO smell on mine. You would never even know the DP s were there except for the quick turbo spin-up and louder (throatier) exhaust note.
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      08-19-2013, 11:54 AM   #21
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Quote:
Originally Posted by noushy View Post
Interesting that was my thought. AMS went with 300 cell instead of the 200 cell Porsche, Nismo and others use. I suspect the 400 is better with less rattling and more stock sound but a slight bit more restriction. I wish we had a choice between 200-400 as now knowing what I do I would have chosen 400 for a little less noise, smell and rattling. I do get a bit of smell at startup until the cats heat up which I suspect the larger cell size takes more time.

Noushy
Hey Noushy,

I had some rattling near but not at idle before the DP's with my Meisterschaft. I actually had written it down awhile back to remind me service advisor to check it out. I was going to wait for my first major service in a few thousand miles but now the DP's are making me deal with it immediately. If it were a backpressure issue, I suppose everyone with an aftermarket exhaust would have less backpressure and a looser actuator/wastegate even before decreasing that further with DP's. Anybody able to capture boost levels? Noushy, Hunter?

Mark
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      08-19-2013, 12:22 PM   #22
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Ok I was going to get the AMS catted this week and I too have the Full Meister Exhaust (header back)... but no power gains are slightly concerning along with this rattle bull shit.
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