BMW M5 Forum and M6 Forums banner

1 - 20 of 56 Posts

·
Registered
Joined
·
62 Posts
Discussion Starter #1
I know that people have taken out the secondary cat when they put on their Eisenmann exhaust.

My question is, has anyone taken off the cat on stock exhaust? If so, how does it sound?


thnx!
 

·
Registered
Joined
·
503 Posts
I have 2nd cat delete and replaced sect II or resonators with x-pipe along with Tubi mufflers. Here's a sound bite of mine if you haven't seen it already. Hope this is what you were looking for.

BTW: I absolutely love it. It sounds so much better in person. No trouble in the cabin.

http://www.youtube.com/watch?v=amTRbHkXcHc
 

·
Registered
Joined
·
503 Posts
Keang24 is right. When I bought from eisenmann they said it should pass because of the primary still in place. Then, I take it to my muffler guy and he says it mostlikely will not pass smog here in Cali. I kept sect. 1 just for that reason. When the time comes I will try for a pass unless someone in cali says they failed with secondary cats deleted.

The sound is awesome and well worth it. It also seems like it has added strength the car.
 

·
Registered
Joined
·
386 Posts
It shouldn't be a problem seeing how they will just plug in the OBDII reader and see if there are any errors. If you don't have a service engine soon light there shouldn't be a problem.
 

·
Registered
Joined
·
62 Posts
Discussion Starter #9
Sorry for the miscommunication, but i was asking the cat question for sound purposes not smog...
 

·
Registered
Joined
·
3,967 Posts
Sorry for the miscommunication, but i was asking the cat question for sound purposes not smog...
sorry again, got mess-up with FogPuppy comment.

Yes. the 2nd cat deleted will give a little raspy groaning from the midsection. I have 2nd cat/resonator deleted with stock muffler for about a week while waiting for a new exhaust, so I definitely noticeable with 2nd deleted. Not much louder, just more raspy
 

·
Registered
Joined
·
503 Posts
To add to the decription of sound and raspiness, since I recently deleted secondary cat, I already had x-pipe, what I noticed was the raspiness, increase in sound starting at 3000 rpm's. This is much sooner than before. Also, a lot louder start up warm up phase.

I also believe there feels like greater power. I am finding the wheels are spinning a lot more than ever before.
 

·
Registered
Joined
·
307 Posts
No one has taken off 2nd cat on STOCK exhaust??
You might PM Darren_Dallas, I know he had his secondary cats removed w/ Eisenmann race for a while. He also installed headers and then put his stock exhaust back on b/c it was insanely loud. He was having issues with emissions errors, check engine light, etc. and I think he ended up having to replace the cats to pass inspection. Also the guy that did the initial work kind of jacked up the install and I'm sure that didn't help. In the end he got all the faults and errors cleared and got his car inspected. If he sees this thread I'm sure he will elaborate. Also I know he purchased software hoping that would correct the faults and enable his car to pass. Unfortunately the only thing the software does is turn off the check engine light, it does not remove any faults.
 

·
Registered
Joined
·
503 Posts

·
Registered
Joined
·
3,886 Posts
Just remembered who has that set up. Mike, AKA Wolverine. Don't think there's a sound clip. http://www.m5board.com/vbulletin/showthread.php?t=102285
Haven't removed the secondary cats, just the resonator. I'd take the cats out in a heartbeat if there were real hp gains, and no noise problems. I've heard there is some 'raspiness' or resonance at certain rpms if you remove them though, and no real hp gains.
 

·
Registered
Joined
·
3,263 Posts
I'm not sure I understand the threads original question? Are you asking about removing the secondary cats, ie. section 1, and put back the rest of the stock exhaust?
If that's the question I've not heard of or seen anyone do that. Do not know if it has any effect on the sound or power. Probably not.
 

·
Registered
Joined
·
503 Posts
Haven't removed the secondary cats, just the resonator. I'd take the cats out in a heartbeat if there were real hp gains, and no noise problems. I've heard there is some 'raspiness' or resonance at certain rpms if you remove them though, and no real hp gains.

Ahh, you must have been just toying with the idea from what I remember. I did it. From the feel of things it seems that my butt monitor is saying a 8 hp gain 10-12 in torque:margarita:. More so than ever. Then again, it might be it is cooler now and I also have the filters. Nevertheless, it sounds awesome!

still need to get this thing on the dyno.
 

·
Company Representative of RPI Power
Joined
·
3,395 Posts
I dyno'd each section separately. You can see what the section 1 (secondary cat removal) did here:

http://www.m5board.com/vbulletin/showthread.php?t=96799

It increased the torque from down low to about 3500rpm, then there is a slight loss for about 1000 rpm, then a gain to near redline.

Noise wise, you definitely noticed the increase in sound. It also took a bit of the smoothness away, giving the exhaust tone during the rev up a more raspy bark.
 

·
Registered
Joined
·
22 Posts
I'm installing the Eisenhaus system soon; section 1 and 2 included. When deleting the secondary cats, what's necessary to avoid the "service engine soon" fault? I see lots of choices for software upgrades to disregard such emissions faults, but they tend to be more than just a bypass software and rather a performance software designed for headers +.

I just want to avoid the SES fault only since I'm not replacing the headers right now.

Thanks in advance,

Nick
 
1 - 20 of 56 Posts
Top