Horrendous Sound Downpipes and Midpipes!!!

[robertm]

Everyone has their own motivations, preconceptions and opinions as to why they do what they do to their own car. That’s what makes the modding experience great and it also provides a market for multiple vendors.

I will say from my experience (if I actually had them – which I don’t of course) that adding DPs will be the single biggest noticeable engine mod you can add outside of software. The turbo spool up response is noticeably quicker and the top end 'choke out' our engines experience is notably decreased. I assume there is some power gained too but I don't feel any mods before software add enough power to make 'that much' of a difference. You can definitely feel the difference in how quickly the turbo spools up with catless DPs.

Also, catless DPs with catless center section along with a free flowing intake makes great sounds without any drone that I’ve noticed. It’s by no means TOO loud and I’ve gotten lots of compliments. You can hear the motor a lot better now and there are all kinds of cool turbo spool up noises. This is in combination with the factory axle back mufflers. If you already have a free flowing axle back then adding catless DPs may very well become too loud.

With regards to the smell. I notice it when I pull into the garage but that’s really about it. I’ve never had issue with windows down driving and smell. I suppose if you are at a dead stop and windows down and wind is blowing at the perfect angle and you are reving the engine then you could get some exhaust smell but it’s never happened to me.

With regards to post cat O2 sensor. The BMS O2 simulator takes about 20 minutes to install and works perfect. As long as you don’t get an actual sniff test at State inspection it will never be an issue. All they do is plug into OBD II and scan for codes. Just as an aside to this, I am pretty certain a couple 2” O2 spacers would work just as well. I’ve had luck with them on other cars and they are used almost universally in the ricer scene. Someone could try them out if so inclined.

Someone said you might get in trouble with the police if you get pulled over. Never in all my life have I heard of someone getting pulled over and that turning into getting the car on a lift to see if it's equipped with cats. That's just way to far fetched. You should have your vehicle shut off long before the cop gets out of his car and reaches you anyways..

EDIT: (1/7/2014)

I just came across this post I made a year ago. Since people are still reading this stuff I figure I better update. I can not recommend the BMS O2 simulator as a long term solution. After speaking with Terry and others I've discovered that over time this will throw the fuel trims out of sinc. This is really just supposed to be a temporary solution (ie get you past emissions testing then take it off). After several months on the car the pre cat sensors will use the post cat sensor signal to recalibrate itself. Since the post cat signal is faked it ends up slowly getting things out of whack. So, I recommend installing for emissions testing, then removing. After that live with the service engine light or go with an after market tune solution to fix the issue. Mechanical O2 spacers would probably work too but I haven't gotten around to trying it.

[MDORPHN]

I've been in 1Ms with catless downpipes -- once in combination with a N55 midpipe and another with the stock midpipe.

In both situations, the sound was fine. A little deeper than stock with bit of "gurgling" and significantly less drone.

The smell of gas was, of course, apparent with the fully catless set-up. However, with the stock (catted) midpipe, it was only detectable upon start-up.

Neil

[widbimmer]

Originally Posted by MDORPHN

I've been in 1Ms with catless downpipes -- once in combination with a N55 midpipe and another with the stock midpipe.

In both situations, the sound was fine. A little deeper than stock with bit of "gurgling" and significantly less drone.

The smell of gas was, of course, apparent with the fully catless set-up. However, with the stock (catted) midpipe, it was only detectable upon start-up.

Neil

With every post I get more and more confused!

I had the AR downpipes and the madDad mids installed with the original gaskets and the sound was horrible, pretty much like a rusty old car between 1500 rpm and 5000 rpm... after 5000 rpm it sounded deeper and cool

Now I only have the madDad midpipes with the stock gaskets and it sounds very good over 3000 rpm but when I'm in any gear at very low rpm it makes a very anoying noise...

I think I'll give the DPs a chance again but with the AR gaskets....

*Just for you guys to know... I don't have emissions or noise issues here in my country so DP's are allowed unless you are in a residential area and start drifting or making unecessesar noise....

[MDORPHN]

Originally Posted by widbimmer

With every post I get more and more confused!

I had the AR downpipes and the madDad mids installed with the original gaskets and the sound was horrible, pretty much like a rusty old car between 1500 rpm and 5000 rpm... after 5000 rpm it sounded deeper and cool

Now I only have the madDad midpipes with the stock gaskets and it sounds very good over 3000 rpm but when I'm in any gear at very low rpm it makes a very anoying noise...

I think I'll give the DPs a chance again but with the AR gaskets....

*Just for you guys to know... I don't have emissions or noise issues here in my country so DP's are allowed unless you are in a residential area and start drifting or making unecessesar noise....

I'd guess that there is an installation issue causing the nasty noise. Among other things, sounds like the downpipes may be coming into contact with the subframe.

Neil

[bdaddylo]

Sorry, but without a sound clip, this thread is pointless. Everyone has a different opinion of what sounds good.

Your issue below 3,000 rpm is probably drone if it's a low frequency bass sound that is annoying to your ears and head. Although I find it strange, some people actually like drone.

[widbimmer]

Originally Posted by bdaddylo

Sorry, but without a sound clip, this thread is pointless. Everyone has a different opinion of what sounds good.

Your issue below 3,000 rpm is probably drone if it's a low frequency bass sound that is annoying to your ears and head. Although I find it strange, some people actually like drone.

I understand that some people would like a sound clip.... So I will try to install the DP's again this week in another place an post a sound clip if the horrible sound comes out again... With mids the car sounds really good I hope that this time the DP's and Mids sound good together.....

[Chachirims]

If you want the install done right and have piece of mind, take it to the dealer. They installed a full Akra exhaust on Paolo Guerreo's 1M and retuned it.

[///1M]

Originally Posted by Chachirims

If you want the install done right and have piece of mind, take it to the dealer. They installed a full Akra exhaust on Paolo Guerreo's 1M and retuned it.

I'm confused... are you saying that the BMW dealer will install certain aftermarket exhaust systems?

[ozinaldo]

Originally Posted by ///1M

I'm confused... are you saying that the BMW dealer will install certain aftermarket exhaust systems?

Southern Hemisphere! Everything and everyone upside down around here

Seriously, my BMW dealer once even tried to warn me about the warranty risks of installing PSS tires outside the dealership and he got his answer of course.

[e82m_van]

Hey op, I know what sound you are talking about..
I just installed catless downpipes on my car, mated with n55 mids.
It sounds really bad.. around 2100 rpm. it goes like ehhhhnnnnngggggg hahahha lol

Also, I'm the type that likes to drive with my windows open as much as possible. But going completely catless, I don't think I can do it.. which is another reason why I'm planning on putting the oem dps back on.

But here is what I was wondering.
If smell or noise isn't the problem, would you go catless downpipes or catless midpipes?

[Alexim]

Originally Posted by e82m_van

Hey op, I know what sound you are talking about..
I just installed catless downpipes on my car, mated with n55 mids.
It sounds really bad.. around 2100 rpm. it goes like ehhhhnnnnngggggg hahahha lol

Also, I'm the type that likes to drive with my windows open as much as possible. But going completely catless, I don't think I can do it.. which is another reason why I'm planning on putting the oem dps back on.

But here is what I was wondering.
If smell or noise isn't the problem, would you go catless downpipes or catless midpipes?

I just did the same thing.. Kittyless DPs and removed the cats from the mids and welded on a straight pipe... The sound is exactly at around 2100rpm... and also when cold starting, it yells that weird sound for a few secs...
No way I'm getting the cats back on, so my bet is some resonated mids and aftermarket axleback...

[diegorst]

Were the problems with the DPs finally solved? I'm really interested as I am planning on installing AR DPs to my current set up now that I've upgraded the FMIC.
Any sound clips of AR DPs?

[Mr Kleen]

Bumping an old thread as I'm having a similar issue. I have an N55 with a Berk DP and I just purchased a used MadDad whisper exhaust and it drones like CRAZY. New gaskets, new spring bolts, everything torqued down. Not sure what the issue is but mid-throttle drone is literally headache inducing.

[robertm]

I just edited the post I made last year. Figured I'd copy paste in a new post so that people don't miss it.



After speaking with Terry and others I've discovered that over time the O2 simulator will throw the fuel trims out of sinc. This is really just supposed to be a temporary solution (ie get you past emissions testing then take it off). After several months on the car the pre cat sensors will use the post cat sensor signal to recalibrate itself. Since the post cat signal is faked it ends up slowly getting things out of whack. So, I recommend installing for emissions testing, then removing. After that live with the service engine light or go with an after market tune solution to fix the issue. Mechanical O2 spacers would probably work too but I haven't gotten around to trying it.

[moveswiftly]

It may be a raspy? If that's what you're trig to explain?

[mrow]

Stock DPs, MadDad mids and stock axel back. After about 1000 miles on the MadDads it sounds fucking awesome IMO.

[MrBimmer]

Hey guys, its been a while since ive been on the forums... kinda took a break BUT!!
now that i am back and interested in outfitting my 1M with some parts i want to add a few things to this thread.

Maddad made a DP which was part of a set called the whisper quiet exhaust system. Wouldn't that dp work on the 1M ? the set includes the dp midpipe and rear section ( which obviously we wouldnt be able to use) Has anyone ever tried the quiet dp and mid combo on stock axel back combo before? Oh and i believe that there is a difference between the maddad 135i midpipe and the 1M maddad midpipe so perhaps the extra noise could be caused by having the 135i version of the pipe.

Also, i noticed that a few people mentioned that the 1M DP is an improvement over the 135i DP. ive also seen where people were saying that setting the COBB AP to stage 2 on stock exhaust was doable. Is it safe?

[a7med606]

Originally Posted by MrBimmer

Hey guys, its been a while since ive been on the forums... kinda took a break BUT!!
now that i am back and interested in outfitting my 1M with some parts i want to add a few things to this thread.

Maddad made a DP which was part of a set called the whisper quiet exhaust system. Wouldn't that dp work on the 1M ? the set includes the dp midpipe and rear section ( which obviously we wouldnt be able to use) Has anyone ever tried the quiet dp and mid combo on stock axel back combo before? Oh and i believe that there is a difference between the maddad 135i midpipe and the 1M maddad midpipe so perhaps the extra noise could be caused by having the 135i version of the pipe.

Also, i noticed that a few people mentioned that the 1M DP is an improvement over the 135i DP. ive also seen where people were saying that setting the COBB AP to stage 2 on stock exhaust was doable. Is it safe?

dont set the cobb to stage 2 because it requires DP , cobb have maps that is specialized for the 1m and its different than the 135i or 335i maps , so if you want to set it to stage 2 you should have downpipes .

something about the thread , i am planning to get AR catless down pipes , after watching some YT videos , i think i will get it and get a resonated mid's with either eisenmann exhaust with their resonated mids , or HMS axle back with the stock mids or N55 .