AMS Catless Downpipes - Potential Problems?

[AlphaAlpineM6]

I've purchased and am in possession of the new AMS Alpha catless downpipes. I'm excited, however, after further research and review I've been holding off on installing them.

"Catalytic converters decrease the exhaust velocity and limit flow, increasing pressure behind the impeller wheel and limiting the turbo's top speed -

Removing the cats, decrease backpressure and as a result the turbochargers spool faster and higher"

I am not confident enough to take my chances and assume the computer will "adapt", understand, or assume they're maps for different boost at certain RPMs.


How can tuners be so sure the ECU will adapt if no one has actually read the codes and maps in the ECU.

"The current maps that are on the market are either development maps; designed to have more power than production for journalists to write glowing reviews, or piggyback systems"

Some user suggest waiting till tuners have cracked the ECU to compensate for the extra boost. If this is the case my car will never see these downpipes because I have no intention on tuning this car, because of warranty issues.


AMS Alpha tuning, I have contacted your sales and support department on August 13. I was given a verbal, "no you will not see any issues".

This car will see the racetrack a few times a year and will be at most of the airstrip events hosted by shift-s3ctor, a simple - "no you will not see any issues" is not sufficient enough to relieve my worry.

When I brought up more technical questions the gentleman on the phone admittedly wasn't able to answer - He said to leave my number and expect a return phone call from the tuner or tech.

To be clear I put my trust in this company as an aftermarket tuner because of the previous work they've demonstrated with turbocharged motors. They will not lose my trust until I have ran into an issue as a result of their product.

Including related problems that may cause factory warranty issues.

I welcome all tuners including AMS to clear things up here on the board - looking forward to installing these downpipes.

--
Alpha

[AMS ALPHA]

The tune for the stock car will work quite well. Here is why:

The ECU is load dependent and is always striving to achieve the same load, no matter what you do to it. It has the ability to manage torque in many different ways, which includes, but is not limited to; Throttle, ignition timing and boost control.

What that means is that although there may be less restriction as you mentioned, the ECU will constantly be providing feedback as to how much load and torque is being transmitted and adjust all the parameters in order to compensate and match its goal. Any horsepower gains are from a loss of restriction as well, and not because of a boost increase. In fact if the car is using the boost adequately, the boost will be LOWER than a stock car, and yet make more power. This is because the boost is only a measure of restriction of air waiting to enter the cylinders. When air can enter the cylinders easier than before because of a loss of restriction (anywhere in the system), the boost level will drop and it will make MORE power.

While the turbos may be spinning slightly faster than they were before, I am positive that they aren't spinning any faster than they would with a stock car which has one of the development tunes on it. Also, the back pressure will be less, and the car is now running more efficiently and creating less heat. So in a way it is even safer than it was before.

I hope that helps

Eric

[RPiM5]

Eric makes a lot of good points. I've been running catless downpipes now for over 5,000 miles. Not a single problem. So far I've seen quicker spool up time from the turbos, ZERO turbo lag, lower operating temperatures, and greater sound from the removal of the Cats.

The stock ECU can absolutely adapt. After about 500 miles with the new catless downpipes on, I really felt the difference in power and torque after the ECU had adapted. I was still feeling the ECU adapt all the way to about 1,000 miles. The stock ECU will still maintain it's stock programming and will not let the boost go any higher. When I dyno'd, I did not really see any gain in peak horsepower but I saw a small gain in peak torque. However, I gained about 50hp and 50tq in the mid-range over the stock downpipes. The difference is quite noticable. Removing the cats really changed the entire character of the F10 M5. It's basically how the car should have come from BMW in my opinion. Just put them on, you'll love it!

[Nate@IND]

Originally Posted by AMS ALPHA

The tune for the stock car will work quite well. Here is why:

The ECU is load dependent and is always striving to achieve the same load, no matter what you do to it. It has the ability to manage torque in many different ways, which includes, but is not limited to; Throttle, ignition timing and boost control.

What that means is that although there may be less restriction as you mentioned, the ECU will constantly be providing feedback as to how much load and torque is being transmitted and adjust all the parameters in order to compensate and match its goal. Any horsepower gains are from a loss of restriction as well, and not because of a boost increase. In fact if the car is using the boost adequately, the boost will be LOWER than a stock car, and yet make more power. This is because the boost is only a measure of restriction of air waiting to enter the cylinders. When air can enter the cylinders easier than before because of a loss of restriction (anywhere in the system), the boost level will drop and it will make MORE power.

While the turbos may be spinning slightly faster than they were before, I am positive that they aren't spinning any faster than they would with a stock car which has one of the development tunes on it. Also, the back pressure will be less, and the car is now running more efficiently and creating less heat. So in a way it is even safer than it was before.

I hope that helps

Eric

Big

We have been running the AMS catless downpipes on the iND F10 M5 for a few months. Tons of power and zero issues at all.

[ddrreeww]

Nate,

Correct me if i was wrong, with ams catless dp, the CEL is on and there is no way to remove it, rite? So you are sayong, other than this CEL, everythg runs fine w ams catless dp??

Any potential problems in looonng run?? Any problems at all??? If i ever hav to be back to factory n they see the CEL is on, what would most likely to happen????

Thx.

[Nate@IND]

Originally Posted by slowcarsonfastlane

Nate,

Correct me if i was wrong, with ams catless dp, the CEL is on and there is no way to remove it, rite? So you are sayong, other than this CEL, everythg runs fine w ams catless dp??

Any potential problems in looonng run?? Any problems at all??? If i ever hav to be back to factory n they see the CEL is on, what would most likely to happen????

Thx.

The same Supersprint micro cat set was tested on US Spec M5's and did not work. I checked with my contact in Germany and he informed that the Euro Spec emissions sensors are not as sensitive as the US spec M5's. My guess is the micro cats were tested on a Euro spec F10 M5 which did not get a CEL.

The CEL from "increased emissions" on the US spec M5 does not cause any harm at all. All you will get is a light on the dash letting you know that there is a problem with the sensor or cats. Once a real tune hits the market you can simply shut the light off.

[boots]

If I can stay in town long enough I will place my order Nate.

[boots]

Hurry and post up vids pert.

[noushy]

All I can say is the sound is intoxicating, at times loud but very exotic out of the Akra + AMS. I am a customer for life with AMS.

Noushy

[MasterDank]

IND & AMS are top notch..... 4,000 amazing miles with mine.... I love them!!!

Aloha
Alex

[shady908]

How much/how long did the downpipes take to install? I know I read a thread about someone having their dealer install them...

[Rob///M5]

Originally Posted by shady908

How much/how long did the downpipes take to install? I know I read a thread about someone having their dealer install them...

3-4 hours @ EAS

[F12M6MD]

Thinking about removing my AMS catted downpipes.

The increase in rattling from the engine bay (my mechanic said it is from the wastegates) is just too prominent and I can hear it coming off any load below 3000rpm all the way down to idle. I can rev in neutral and hear it coming down as well as during driving coming down off revs. At idle it is not audible. Any of you hear this same noise? Thanks for your input.

Mark

[cpiguy]

Originally Posted by F12M6MD

Thinking about removing my AMS catted downpipes.

The increase in rattling from the engine bay (my mechanic said it is from the wastegates) is just too prominent and I can hear it coming off any load below 3000rpm all the way down to idle. I can rev in neutral and hear it coming down as well as during driving coming down off revs. At idle it is not audible. Any of you hear this same noise? Thanks for your input.

Mark

Hey Mark, even though you're frustrated with the rattling noise, did you see a significant performance improvement with the DP's? I was just getting ready to order the same ones. Also, how much louder was it? I have the Meistershaft Cat back system as well. Would you say it is a noticable diference beyond the MS exhaust system?

Thanks

[Grayblack]

I just had my AMS catted dp's installed yesterday. The sound has really opened up. My exhaust now screams during cold starts. I also noticed cracks when up shifting. I have no confirmation that my hp has increased but it sounds like I'm going a lot faster : )

[RPiM5]

Originally Posted by F12M6MD

Thinking about removing my AMS catted downpipes.

The increase in rattling from the engine bay (my mechanic said it is from the wastegates) is just too prominent and I can hear it coming off any load below 3000rpm all the way down to idle. I can rev in neutral and hear it coming down as well as during driving coming down off revs. At idle it is not audible. Any of you hear this same noise? Thanks for your input.

Mark

Put your throttle response setting to sport mode and you will no longer hear the wastegate flutter when "coming off any load" as you say. Lol!

http://f10.m5post.com/forums/showthread.php?t=872199

[F12M6MD]

Originally Posted by cpiguy

Hey Mark, even though you're frustrated with the rattling noise, did you see a significant performance improvement with the DP's? I was just getting ready to order the same ones. Also, how much louder was it? I have the Meistershaft Cat back system as well. Would you say it is a noticable diference beyond the MS exhaust system?

Thanks

Hey cpi,

No before/after difference on a Dynojet. But that was on the same day. My installer convinced me that the DME did not need more than 20 miles to adjust for full throttle exercises. Seat of pants though (like others have said) it sounds like your going a hell of a lot faster. In fact, I feel like I'm tearing by people a little quicker. If anything, throttle response has improved quite a bit. I'll give it some time to adjust if I don't yank because of the wastegate rattling.

Mark

[F12M6MD]

Originally Posted by RPiM5

Put your throttle response setting to sport mode and you will no longer hear the wastegate flutter when "coming off any load" as you say. Lol!

http://f10.m5post.com/forums/showthread.php?t=872199

Hey rpi,

I mostly drive in Sport Plus and S3. Still rattles "coming off load". Are you guys just tolerating this?

Mark

[Niko1414]

Originally Posted by F12M6MD

Hey rpi,

I mostly drive in Sport Plus and S3. Still rattles "coming off load". Are you guys just tolerating this?

Mark

Not good....

[AlphaAlpineM6]

Originally Posted by F12M6MD

Hey rpi,

I mostly drive in Sport Plus and S3. Still rattles "coming off load". Are you guys just tolerating this?

Mark

I'm returning on my business trip tomorrow and plan on installing the catless DPs paired with the stock mufflers, this Tuesday.

I won't be happy with "rattling".

Now lets be clear about what's going on.

Mark -

A: the waste gates are operating the same way they did out of the factory and the downpipes are simply amplifying the sound. or -

B: the waste gates are not operating the same way they did stock. perhaps the extra exhaust flow is causing the waste gates to rattle and ultimatly malfunction.

?

[Tylerstar]

All I know is I heard these downpipes with a straight pipe exhaust this weekend and I can tell you that it is loud! Idle is crazy!

[boots]

Who's car we're you listening to?