BMW M3 Forum (E90 E92)

BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   M3Post - BMW M3 Forum > E90/E92 M3 Technical Topics > DIY Guides/ Discussions
 
Post Reply
 
Thread Tools Search this Thread
      11-22-2010, 02:29 AM   #1
erics02wrx
?
United_States
48
Rep
125
Posts

Drives: E90 M3
Join Date: Aug 2010
Location: Snohomish WA

iTrader: (0)

Arrow DIY: OEM x-pipe secondary cat removal/gut

Looking for an after market x-pipe with secondary cat delete and resonators for your car? How about modding your OEM exhaust! There is VERY LITTLE difference between the aftermarket x-pipes and the stock one! BMW has built a very good quality exhaust system from the factory and it needs only a few minor tweaks to squeeze out the extra hp. I was looking for a x-pipe with 2nd cat delete with resonators but could not understand how the manufactures could justify there pricing, they must think we have $ to burn or that most M3 owners just believe the hype and buy

The secondary cat delete (Gut the factory cats) is very easy and only took me about 3 hours total including removal, modifying and reinstall. This is one of the best improvements i have done to the car. It will make the engine more responsive and should add around 8-15hp for $0.00 and a little bit of your time. If you are not the DIY type then an exhaust shop should be able to do this for less than $150-200.

+ The best part is the dealer will have no clue it is modded, it looks stock


So here is the process of doing a secondary cat gut / delete:

1. remove the x-pipe portion of the exhaust from car, you can leave the rear sip-on exhaust on the car
2. you will need to mark the exhaust pipe with 2 or 3 parallel lines on each pipe because you will use these later when you are realigning the exhaust tubing for welding. Now using a cut off wheel, cut the slip joint right behind the weld at the front of secondary cats. Be careful and only cut through the outer pipe wall, not all the way through


3. now this is what the 200cell secondary cats look like


4. just for reference, these are the tools that i used

5. (PUT ON DUST MASK) take your 1/2 HD drill and use a 3/4" +/- self feed spiral drill bit to remove the majority of the catalyst. If you try to just pound it out it will compress into a hard metal mass that will lodge itself inside the exhaust tubing(trust me) Remove most of the catalyst material and then use the pipe to scrape and push out the left over material. You should have a pile of catalyst like this from the first cat

and this is what it should look like with the first cat removed/gutted

6. now do the same for the next one and your pile of catalyst on the floor should look like this

7. you will need to rig up a wire brush on a piece of pipe and clean-up the inside of the exhaust pipe, it doesn't need to be perfectly clean just get most of the catalyst out


8. now that you have the gut complete you are ready to reassemble

9. you should now be able to realign the exhaust using the alignment marks you made at the beginning. I used a small MIG welder to weld the exhaust tubing back together. You will need to do a series of tack welds around the exhaust tubing as to not burn through, or set your welder to the lowest setting, this is very common for exhaust tubing.



10. if you are trying to be stealth then nows the time to clean up the welds

and this is what it should look like, once it gets a Little heat coloring on it the dealer will have no clue that it is modded!


In addition to what I wrote at the beginning, I did this mod so that I would not have to deal with a CEL and then a tune, and the inevitable chance that the dealer will reflash the car while in for service. I would then lose my tune and have to pay for it to be reflashed to the ECU, its just not worth it to me for an extra 10-15 whp that a tune gives you. I will probably in time gut the main OEM cats also, I just need to find a good CEL fix that the dealer won't find. Most of the hp people are getting out of our cars are from the removal of the cats (20-30 whp) NOT THE TUNE! (10-15 whp). I drive my car hard at the track and I want to know that if something goes wrong with the car, the dealer will have less to complain about and no reason to say I voided my warranty.

Hope this helps some of you that are thinking of doing this mod.......
__________________
08 E90 M3, slick top, single hump, 6MT

Last edited by erics02wrx; 11-22-2010 at 10:52 PM..
Appreciate 0
      12-07-2010, 10:55 AM   #2
1sikbmr
Brigadier General
1sikbmr's Avatar
145
Rep
3,329
Posts

Drives: F80 M3 6MT
Join Date: Mar 2010
Location: New York

iTrader: (16)

This is awesome... Going to save me 1k.... Thanks....

Quick question... How exactly did you clean up the welds? I want to do that also but dont want to mess it up...
__________________

F80 ///M3 6MT Avus Blue ZCP
Appreciate 0
      12-07-2010, 11:54 AM   #3
andrew270681
Private First Class
andrew270681's Avatar
Australia
9
Rep
164
Posts

Drives: E92 M3
Join Date: Nov 2010
Location: Sydney, Australia

iTrader: (2)

Great Write up!

Do you notice any increase in power after doing this?
Appreciate 0
      12-08-2010, 09:16 AM   #4
BT M3
Second Lieutenant
12
Rep
214
Posts

Drives: 2010 M3
Join Date: May 2010
Location: MA

iTrader: (0)

This is incorrect information from my dyno findings. A proper custom tune will yield 15-20whp. And the secondary cats are maybe worth 10hp and some noise. The primaries delete are worth alot more as the design is far more restrictive.
Appreciate 0
      12-08-2010, 11:09 AM   #5
erics02wrx
?
United_States
48
Rep
125
Posts

Drives: E90 M3
Join Date: Aug 2010
Location: Snohomish WA

iTrader: (0)

Quote:
Originally Posted by BT M3 View Post
This is incorrect information from my dyno findings. A proper custom tune will yield 15-20whp. And the secondary cats are maybe worth 10hp and some noise. The primaries delete are worth a lot more as the design is far more restrictive.
Your right on and that is what I was saying! I was not stating that the secondary delete alone was going to get you the same hp as no cats+tune or even main cats+tune. What i was saying is that the power that people are getting out of tunes is directly related to the cats....if you left the cats in place and got a reflash you would only pick up 7-12 whp max ( less than just doing a secondary cat delete and rear slip on, which would not cause any issues from a warranty standpoint like a tune could) Remove the main and secondary cats and even without a tune you will pick up 20whp+.....add a tune to the cat removals and you will add an additional 10-15whp! My point is most of the gains people are getting are not from the tune but from the removal of the cats(65% from secondary and main cat delete and 35% from tune). There is not a lot of hidden hp in this engines tunning parameters stock, you have to really start changing things(cams, pulleys, intake, exhaust, TB, headers, etc....) before you are going to see big gains from a tune.
__________________
08 E90 M3, slick top, single hump, 6MT
Appreciate 1
      12-08-2010, 11:19 AM   #6
erics02wrx
?
United_States
48
Rep
125
Posts

Drives: E90 M3
Join Date: Aug 2010
Location: Snohomish WA

iTrader: (0)

Quote:
Originally Posted by 1sikbmr View Post
This is awesome... Going to save me 1k.... Thanks....

Quick question... How exactly did you clean up the welds? I want to do that also but dont want to mess it up...
Look at #10 and you will see me using a right angle die grinder with a 100grit sand paper wheel on the end of it. It is not quite as fast but way cleaner than using a grinder which would leave large grind marks that the dealer could see. If you have a lot of weld to remove, start with a grinder and then finish it up with the sanding disk.
__________________
08 E90 M3, slick top, single hump, 6MT
Appreciate 0
      12-08-2010, 11:36 AM   #7
erics02wrx
?
United_States
48
Rep
125
Posts

Drives: E90 M3
Join Date: Aug 2010
Location: Snohomish WA

iTrader: (0)

Quote:
Originally Posted by andrew270681 View Post
Great Write up!

Do you notice any increase in power after doing this?
I have not had it dynoed, but probably only 5-8 rwhp. The big diferance was it makes the engine feal more responsive. I also have the Corsa⁄UUC Exhaust on my car and i noticed a lot more gains in top end pull with the secondary cat delete over just the rear slip on.
__________________
08 E90 M3, slick top, single hump, 6MT
Appreciate 0
      12-08-2010, 11:15 PM   #8
swamp2
Lieutenant General
swamp2's Avatar
United_States
609
Rep
10,407
Posts

Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

iTrader: (3)

Very nice DIY, thanks for sharing. How is the sound afterwards? Hopefully not too much increase in loudness (unless you wanted that).
__________________
E92 M3 | Space Gray on Fox Red | M-DCT | CF Roof | RAC RG63 Wheels | Brembo 380mm BBK |
| Vorsteiner Ti Exhaust | Matte Black Grilles/Side Gills/Rear Emblem/Mirrors |
| Alekshop Back up Camera | GP Thunders | BMW Aluminum Pedals | Elite Angels |
| XPEL Full Front Wrap | Hardwired V1 | Interior Xenon Light Kit |
Appreciate 0
      12-09-2010, 12:53 AM   #9
erics02wrx
?
United_States
48
Rep
125
Posts

Drives: E90 M3
Join Date: Aug 2010
Location: Snohomish WA

iTrader: (0)

Quote:
Originally Posted by swamp2 View Post
Very nice DIY, thanks for sharing. How is the sound afterwords? Hopefully not too much increase in loudness (unless you wanted that).
Maybe 5% louder than before, no change inside the car. It did add a little more rumble, sounds awesome!
__________________
08 E90 M3, slick top, single hump, 6MT
Appreciate 0
      12-09-2010, 06:03 PM   #10
swamp2
Lieutenant General
swamp2's Avatar
United_States
609
Rep
10,407
Posts

Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

iTrader: (3)

Quote:
Originally Posted by erics02wrx View Post
Maybe 5% louder than before, no change inside the car. It did add a little more rumble, sounds awesome!
Really? Not noticeable in the car? Cool. My aftermarket cat back Vorsteiner set up added some volume and I am really hesitant to make it any louder. The sound quality was really improved for me but I am definitely concerned about doing something that will make long freeway trips and road trips annoying to unbearable.
__________________
E92 M3 | Space Gray on Fox Red | M-DCT | CF Roof | RAC RG63 Wheels | Brembo 380mm BBK |
| Vorsteiner Ti Exhaust | Matte Black Grilles/Side Gills/Rear Emblem/Mirrors |
| Alekshop Back up Camera | GP Thunders | BMW Aluminum Pedals | Elite Angels |
| XPEL Full Front Wrap | Hardwired V1 | Interior Xenon Light Kit |
Appreciate 0
      12-10-2010, 12:36 AM   #11
spoonf20c
let me see you become a ///Monster
spoonf20c's Avatar
Philippines
16
Rep
396
Posts

Drives: F80
Join Date: May 2009
Location: SloCal

iTrader: (15)

nice write up. would the process be the same if i wanted to gut the primaries too? would those be harder to gut and would you be able to put it back together as cleanly.
__________________
Appreciate 0
      12-10-2010, 03:26 AM   #12
alpina527
Banned
United Kingdom
60
Rep
638
Posts

Drives: 2008 E92 M3 DCT JZB/FR
Join Date: Jan 2010
Location: London, England

iTrader: (1)

Quote:
Originally Posted by spoonf20c View Post
nice write up. would the process be the same if i wanted to gut the primaries too? would those be harder to gut and would you be able to put it back together as cleanly.
You can make the cut at the same place to do the primaries, but you will get a cel light.
Appreciate 0
      12-10-2010, 11:18 AM   #13
erics02wrx
?
United_States
48
Rep
125
Posts

Drives: E90 M3
Join Date: Aug 2010
Location: Snohomish WA

iTrader: (0)

Quote:
Originally Posted by swamp2 View Post
Really? Not noticeable in the car? Cool. My aftermarket cat back Vorsteiner set up added some volume and I am really hesitant to make it any louder. The sound quality was really improved for me but I am definitely concerned about doing something that will make long freeway trips and road trips annoying to unbearable.
I have the UUC / Corsa exhaust and I was afraid of the same thing (being to loud) but it was barely noticeable. Its a little louder from the outside of the car but on the inside its maybe 5% louder, if that. I love it!
__________________
08 E90 M3, slick top, single hump, 6MT
Appreciate 0
      12-10-2010, 11:25 AM   #14
erics02wrx
?
United_States
48
Rep
125
Posts

Drives: E90 M3
Join Date: Aug 2010
Location: Snohomish WA

iTrader: (0)

Quote:
Originally Posted by spoonf20c View Post
nice write up. would the process be the same if i wanted to gut the primaries too? would those be harder to gut and would you be able to put it back together as cleanly.
Same process and very easy. You will get a CEL just like alpina527 said..... so you will have to get a CEL fix or tune, I guess you could also just drive it with the cel on, it wont hurt anything but would be very annoying.

Quote:
Originally Posted by alpina527 View Post
You can make the cut at the same place to do the primaries, but you will get a cel light.
__________________
08 E90 M3, slick top, single hump, 6MT
Appreciate 0
      12-24-2010, 01:41 AM   #15
1sikbmr
Brigadier General
1sikbmr's Avatar
145
Rep
3,329
Posts

Drives: F80 M3 6MT
Join Date: Mar 2010
Location: New York

iTrader: (16)

This was great. I just finished it flawlessly... didn't take any pics but do have a vid... I do feel a really different car now. It is way more responsive than before and the exhaust note is just 10x better.
__________________

F80 ///M3 6MT Avus Blue ZCP
Appreciate 0
      12-24-2010, 10:40 PM   #16
erics02wrx
?
United_States
48
Rep
125
Posts

Drives: E90 M3
Join Date: Aug 2010
Location: Snohomish WA

iTrader: (0)

Quote:
Originally Posted by 1sikbmr View Post
This was great. I just finished it flawlessly... didn't take any pics but do have a vid... I do feel a really different car now. It is way more responsive than before and the exhaust note is just 10x better.
Great job, this is one of the best mods I've done also and your right, the sound is awsome......post your vid!
__________________
08 E90 M3, slick top, single hump, 6MT
Appreciate 0
      12-25-2010, 05:03 AM   #17
1sikbmr
Brigadier General
1sikbmr's Avatar
145
Rep
3,329
Posts

Drives: F80 M3 6MT
Join Date: Mar 2010
Location: New York

iTrader: (16)

Quote:
Originally Posted by erics02wrx View Post
Great job, this is one of the best mods I've done also and your right, the sound is awsome......post your vid!
Hey just made a thread with the video we made... we also did a little mini shoot... nothing professional just friends hanging out... Check it out...


http://www.m3post.com/forums/showthr...65#post8560765
__________________

F80 ///M3 6MT Avus Blue ZCP
Appreciate 1
      02-20-2011, 07:34 AM   #18
MosesEMMMY
Enlisted Member
2
Rep
31
Posts

Drives: 09vert
Join Date: May 2010
Location: Atl

iTrader: (0)

I finished mine yesterday and im not impressed by the gains or the sound difference. My car is completely has a complete stock exhaust. I noticed a small gain in responsiveness and small rumble after 3500rpms. overall if you can weld at the house then maybe its worth it. I would not pay a shop 200 smackers to do this. I'm not discrediting what the original post says but I was excited as he was until I drove it and the performance described just was not there. Not being negative, just informative.
Thanks for the write-up, it did go well. One alternative we saw would be to do the cut and weld on the other side of the factory weld so you can put the straps over it and it does not have to be perfect, just flat.
Appreciate 0
      03-09-2011, 07:46 PM   #19
erics02wrx
?
United_States
48
Rep
125
Posts

Drives: E90 M3
Join Date: Aug 2010
Location: Snohomish WA

iTrader: (0)

Quote:
Originally Posted by MosesEMMMY View Post
I finished mine yesterday and im not impressed by the gains or the sound difference. My car is completely has a complete stock exhaust. I noticed a small gain in responsiveness and small rumble after 3500rpms. overall if you can weld at the house then maybe its worth it. I would not pay a shop 200 smackers to do this. I'm not discrediting what the original post says but I was excited as he was until I drove it and the performance described just was not there. Not being negative, just informative.
Thanks for the write-up, it did go well. One alternative we saw would be to do the cut and weld on the other side of the factory weld so you can put the straps over it and it does not have to be perfect, just flat.
Thanks for the feedback, its interesting to see that everyone has different outcomes. Main differance is that you still have a OEM rear section. I have a Corsa exhaust, the improvement was noticeable for me and the sound improved also.
__________________
08 E90 M3, slick top, single hump, 6MT
Appreciate 0
      03-22-2011, 11:32 PM   #20
alpine92m3
Banned
United_States
46
Rep
663
Posts

Drives: 2008 AW e92 m3 coupe
Join Date: Mar 2011
Location: usa

iTrader: (7)

hey i'm thinking about doing this mod! but.. i have already taken out the resonators.. do you think if i do this mod will i run into a cel issue>? and how is the idle is it any different ? and will u pass inspection ? or emissons ?
Appreciate 0
      03-23-2011, 12:57 AM   #21
erics02wrx
?
United_States
48
Rep
125
Posts

Drives: E90 M3
Join Date: Aug 2010
Location: Snohomish WA

iTrader: (0)

Quote:
Originally Posted by alpine92m3 View Post
hey I'm thinking about doing this mod! but.. i have already taken out the resonators.. do you think if i do this mod will i run into a CEL issue>? and how is the idle is it any different ? and will u pass inspection ? or emissions ?
As long as you don't touch the main cats you will have no issues at all. There will be no change in idle, no CEL and it has no effect on passing your inspection. If you get a sniff test as part of your emissions test I believe you will still pass no problem because the secondary cats are only for start-up emissions reduction. WA state does a OBD2 test only, so there is no problems with the mod as its post the o2 sensors.
__________________
08 E90 M3, slick top, single hump, 6MT
Appreciate 0
      03-23-2011, 01:59 AM   #22
donovan
Brigadier General
donovan's Avatar
No_Country
370
Rep
4,167
Posts

Drives: R8 - Ford Raptor
Join Date: Aug 2008
Location: National

iTrader: (17)

YUP! See, but watch people will be to lazy to do this and will start whining and crying to find a reason to buy a 2500 dollar setup lol.
__________________

Audi R8 v10
Ford Raptor
m3e46freak@yahoo.comfor all euro parts!!
ebay/craigslist verified/ m3post/e46fanantics/m3forum/zpost/bimmerforum
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 04:31 PM.




m3post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST