Secondary cat delete or leave well enough alone?

dirte90 · 12-27-2010, 11:16 AM

I am hoping some of you with experience on deleting the secondary cats can chime in with some feedback. I spent a little bit of time trying to find an exhaust combination that I like and now have a setup that I love the sound of. However I know there is some horsepower being robbed by the secondary cats and it would be inexpensive to delete them.

My concern with deleting the secondary cats is that it may change the sound to something I don't care for. Here are some sound clips of what it sounds like with the current setup. What kind of sound change can I expect with the removal of the secondary cats? Is the gain worth the $50 - $75 it will cost to delete them?

A few Revs

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

Takeoff

http://www.youtube.com/watch?v=wXP--jVPcJw

Driveby 1

http://www.youtube.com/watch?v=PaG4mdx8RUg

c_jeong89 · 12-27-2010, 06:20 PM

it's up to u really. are u looking for more sound or just trying to get more power by deleting them? I have them deleted with the bmw perf exhaust and it makes it sound perfect, however u have a muffler delete which is already decently loud. there is another member who did secondary cat delete and muffler delete, akbmw IIRC.

Wlew · 12-28-2010, 12:12 AM

I wonder what it would sound like with no res and the MMW CS muffler?

I have talked with CJeong about it and it should be very similar. But I am afraid about drone. Thats why I got rid of the top speed muffler.

should be fine on inspection since I have the primary cats.

Wlew · 01-02-2011, 01:41 PM

anyone else with some videos of the second cats deleted? cjeong, maybe you could post a link to your videos or the post with them?

c_jeong89 · 01-02-2011, 02:22 PM

The vids I took weren't that good but I also don't think I can capture the sound difference with my camera of the secondaries deleted. It just makes the tone slightly deeper/louder. I can tell u that a friend also a member heard my exhaust and currently he has the bmw perf exhaust with the secondaries still in and he could tell the difference. It's nothing too major, something subtle but noticeable. I like it but here's a video of startup/engine warm/low revs ~2k and lower which u can compare to other bmw perf exhausts on youtube.

AoS810 · 01-02-2011, 04:59 PM

sounds even better in person!

n52330i · 01-02-2011, 07:11 PM

I have removed my secondary cats, and have a Magnaflow muffler installed.

I did feel a bit of HP gains.

It only got a bit louder, now that I installed headers it is too loud.

I think I will get a resonator installed.

jhbimmer · 01-12-2012, 01:35 PM

guys i've been willing to delete the cats but what fears me is it gonna light up errors in the cluster such as "service engine soon" or somethin'?

darkrom · 01-13-2012, 03:42 PM

It will make little to no gains, definitely NONE that you will feel other than in your head, and it will sound slightly louder. Anyone expecting or experiencing sudden gains in power by removing the 2nd cats is just experiencing the placebo effect. You would need to at minimum tune the car differently to actually experience any real gains, and even those would be far less significant than say driving without a passenger.

darkrom · 01-13-2012, 03:43 PM

Quote:

Originally Posted by c_jeong89

The vids I took weren't that good but I also don't think I can capture the sound difference with my camera of the secondaries deleted. It just makes the tone slightly deeper/louder. I can tell u that a friend also a member heard my exhaust and currently he has the bmw perf exhaust with the secondaries still in and he could tell the difference. It's nothing too major, something subtle but noticeable. I like it but here's a video of startup/engine warm/low revs ~2k and lower which u can compare to other bmw perf exhausts on youtube.

Are your lights going crazy or was the camera just picking it up weird? It sounds nice BTW.

mapleridge · 01-14-2012, 04:38 PM

Quote:

Originally Posted by darkrom

It will make little to no gains, definitely NONE that you will feel other than in your head, and it will sound slightly louder. Anyone expecting or experiencing sudden gains in power by removing the 2nd cats is just experiencing the placebo effect. You would need to at minimum tune the car differently to actually experience any real gains, and even those would be far less significant than say driving without a passenger.

Detailaddict dyno'd 5hp and 5lbs to the wheels with his catless set up. Wouldn't deleting cats have similar gains. It's not zero but it is something.

BudVlad · 01-15-2012, 03:43 AM

Quote:

Originally Posted by jhbimmer

guys i've been willing to delete the cats but what fears me is it gonna light up errors in the cluster such as "service engine soon" or somethin'?

You have to use O2 simulators if you remove primary cats otherwise you get errors. Removing secondary cats don’t cause any errors. I removed secondary cats and passed the emission sniffer test with no problem.

kiwi29 · 01-15-2012, 06:18 PM

from what i've heard about secondary cats being deleted, it get louder at higher rpms like a resonator delete would but has more of a "screaming" sound when you are at WOT. I personally love the sound of straight piped cars with a great combination of a wonderful exhaust. If i get my seconds deleted, i'll make sure to post a vid

darkrom · 01-16-2012, 10:25 PM

Quote:

Originally Posted by mapleridge

Detailaddict dyno'd 5hp and 5lbs to the wheels with his catless set up. Wouldn't deleting cats have similar gains. It's not zero but it is something.

5hp is believable IF you have a tune to accommodate that. To simply hack off the cats alone you'd be lucky to even see 1HP IMHO. Maybe even a loss. You really need to have a tune accommodate the cat delete and even then it is not worth the price, but if you are getting a tune already then maybe you would want to do a cat delete before. If you aren't factoring it into a tune I'd say it isn't worth it.

mapleridge · 01-18-2012, 01:25 AM

Quote:

Originally Posted by darkrom

5hp is believable IF you have a tune to accommodate that. To simply hack off the cats alone you'd be lucky to even see 1HP IMHO. Maybe even a loss. You really need to have a tune accommodate the cat delete and even then it is not worth the price, but if you are getting a tune already then maybe you would want to do a cat delete before. If you aren't factoring it into a tune I'd say it isn't worth it.

Check out his dyno. It was done and he had no tune. It is a custom set up though so it can't be said that cutting secondaries would yield the exact same result. Don't know of anyone who dyno'd before and after a straight delete.

Route 16 · 01-18-2012, 03:03 AM

Hate to thread jack. But feeler for my Eisenmann SR pipes if anyone is interested with them.

www.e90post.com/forums/showthread.php?t=636031

http://www.e90post.com/forums/showthread.php?t=608932

FYI Eisenmann SR Pipes are 2ndary cat delete with Eisenmann resonator, no CEL warning since install 6,000 miles and going.

mapleridge · 01-18-2012, 03:16 AM

Quote:

Originally Posted by yoko kai

Hate to thread jack. But feeler for my Eisenmann SR pipes if anyone is interested with them.

www.e90post.com/forums/showthread.php?t=636031

http://www.e90post.com/forums/showthread.php?t=608932

FYI Eisenmann SR Pipes are 2ndary cat delete with Eisenmann resonator, no CEL warning since install 6,000 miles and going.

ohh....a little late...I was looking for pipes to delete the cats a while back. I bought the detail addict set up. This would have been perfect....glws.

Route 16 · 01-18-2012, 03:35 AM

I think Detail Addict would have been the last set up to have in the end anyway so no regret. That's how I feel.

Quote:

Originally Posted by mapleridge

ohh....a little late...I was looking for pipes to delete the cats a while back. I bought the detail addict set up. This would have been perfect....glws.

12-27-2010, 11:16 AM	#1
dirte90 Second Lieutenant 40 Rep 259 Posts Drives: E90 328i Join Date: Sep 2010 Location: SoCal iTrader: (2)	Secondary cat delete or leave well enough alone? I am hoping some of you with experience on deleting the secondary cats can chime in with some feedback. I spent a little bit of time trying to find an exhaust combination that I like and now have a setup that I love the sound of. However I know there is some horsepower being robbed by the secondary cats and it would be inexpensive to delete them. My concern with deleting the secondary cats is that it may change the sound to something I don't care for. Here are some sound clips of what it sounds like with the current setup. What kind of sound change can I expect with the removal of the secondary cats? Is the gain worth the $50 - $75 it will cost to delete them? A few Revs http://www.youtube.com/watch?v=DrKiI_UBqFM Takeoff http://www.youtube.com/watch?v=wXP--jVPcJw Driveby 1 http://www.youtube.com/watch?v=PaG4mdx8RUg __________________
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12-27-2010, 06:20 PM	#2
c_jeong89 Banned 90 Rep 2,097 Posts Drives: E90 TiAg Join Date: Feb 2009 Location: Irvine/Bay Area iTrader: (16)	it's up to u really. are u looking for more sound or just trying to get more power by deleting them? I have them deleted with the bmw perf exhaust and it makes it sound perfect, however u have a muffler delete which is already decently loud. there is another member who did secondary cat delete and muffler delete, akbmw IIRC.
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12-28-2010, 12:12 AM	#3
Wlew Major 77 Rep 1,116 Posts Drives: 2011 E90 335i Join Date: Sep 2009 Location: Washington, DC iTrader: (12)	I wonder what it would sound like with no res and the MMW CS muffler? I have talked with CJeong about it and it should be very similar. But I am afraid about drone. Thats why I got rid of the top speed muffler. should be fine on inspection since I have the primary cats. __________________ 2011 335i Sports Package \| VRSF FMIC \| Cobb AP3 \| Dinan Exhaust \| BMS Intake \| VRSF CP \| Lux H8 Angel Eyes \| Mtec LED Fogs \|
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01-02-2011, 01:41 PM	#4
Wlew Major 77 Rep 1,116 Posts Drives: 2011 E90 335i Join Date: Sep 2009 Location: Washington, DC iTrader: (12)	anyone else with some videos of the second cats deleted? cjeong, maybe you could post a link to your videos or the post with them? __________________ 2011 335i Sports Package \| VRSF FMIC \| Cobb AP3 \| Dinan Exhaust \| BMS Intake \| VRSF CP \| Lux H8 Angel Eyes \| Mtec LED Fogs \|
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01-02-2011, 02:22 PM	#5
c_jeong89 Banned 90 Rep 2,097 Posts Drives: E90 TiAg Join Date: Feb 2009 Location: Irvine/Bay Area iTrader: (16)	The vids I took weren't that good but I also don't think I can capture the sound difference with my camera of the secondaries deleted. It just makes the tone slightly deeper/louder. I can tell u that a friend also a member heard my exhaust and currently he has the bmw perf exhaust with the secondaries still in and he could tell the difference. It's nothing too major, something subtle but noticeable. I like it but here's a video of startup/engine warm/low revs ~2k and lower which u can compare to other bmw perf exhausts on youtube.
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01-02-2011, 04:59 PM	#6
AoS810 Lieutenant 98 Rep 416 Posts Drives: 2008 E90 N51, 2011 E91 N52 Join Date: Oct 2009 Location: Los Angeles, CA iTrader: (6)	sounds even better in person!
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01-02-2011, 07:11 PM	#7
n52330i Second Lieutenant 5 Rep 215 Posts Drives: 330i Join Date: Jan 2011 Location: Mississauga iTrader: (0)	I have removed my secondary cats, and have a Magnaflow muffler installed. I did feel a bit of HP gains. It only got a bit louder, now that I installed headers it is too loud. I think I will get a resonator installed.
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01-12-2012, 01:35 PM	#8
jhbimmer Registered 0 Rep 3 Posts Drives: e90 330i Join Date: Dec 2011 Location: Lebanon iTrader: (0)	guys i've been willing to delete the cats but what fears me is it gonna light up errors in the cluster such as "service engine soon" or somethin'?
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01-13-2012, 03:42 PM	#9
darkrom Colonel 237 Rep 2,341 Posts Drives: 135i Join Date: Feb 2011 Location: Rhode Island iTrader: (5)	It will make little to no gains, definitely NONE that you will feel other than in your head, and it will sound slightly louder. Anyone expecting or experiencing sudden gains in power by removing the 2nd cats is just experiencing the placebo effect. You would need to at minimum tune the car differently to actually experience any real gains, and even those would be far less significant than say driving without a passenger.
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01-18-2012, 03:03 AM	#16
Route 16 I got lei'd 861 Rep 7,606 Posts Drives: '10 E90 M3 Join Date: Sep 2011 Location: Dark Side of the Moon iTrader: (62)	Hate to thread jack. But feeler for my Eisenmann SR pipes if anyone is interested with them. www.e90post.com/forums/showthread.php?t=636031 http://www.e90post.com/forums/showthread.php?t=608932 FYI Eisenmann SR Pipes are 2ndary cat delete with Eisenmann resonator, no CEL warning since install 6,000 miles and going.
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