3.0SE De-Cat

Check the supersprint exhaust kits http://www.supersprint.com/USP0000bmwZ46.asp .
They offer exhaust manifold without cats, and I'm planning to go for that. Practically you will not get but few HPs but the sound of your engine will be much better and by removing the back pressure caused by cats your engine will be relieved. As you can see the price of 1.134,00 eur is big but I know few guys with those exhaust sistems, and is really worth.
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Well Its been done. Cats removed and I can state the following:

* Definite increase in noise. Not that much but a definite improvement
* Much more popping and banging on sudden throttle lifts and revving when the car is stationary :D
* Not much increase in performance although this was expected. If anything id say it revs a little more freely.
* No difference in Fuel economy. Still getting about 27mpg
* I can also confirm that I have no emissions light on the dash either which is a bonus :thumbsup:

Ive attached a little vid that ive just taken now. Excuse the poor quality, I blame the iPhone.

http://img214.imageshack.us/img214/5408/img1244.mp4

Cheers

John
 
Got to hear it's a success. I can't watch the vid as my crappy connection is indicating a 10min download time :roll:
 
I think the main retriction is in the backbox from what ive seen. Removing that plus the lower cats should see around 5-10bhp easily. So your half way there :thumbsup:
 
chris said:
So your half way there :thumbsup:
.... To deafening the neighbourhood!! :rofl: :rofl:

Yeah im gonna be doing things the opposite way round :) Great video John, definitely sounds more aggressive! Love the crackly pops in the upper RPMs!
 
Sounds good dude...! migth give this a go this weekend,just a bit broke at the moment!Is there alot of weigth saving removing the cats? Or more with the backbox?(back box's are soooo heavy)
 
Thanks for the replies guys. I have to say It does sound good.

I was thinking of removing the back box completely and just having a twin stainless section with new exit pipes (style to agree) in place of the box. Do you think this will be rediculously loud, bearing in mind that there is still the pre-cats and resonators in place? I just want a nice sound with some good bangs and pops, nothing that sounds like a sooped up corsa with a Heinz baked bean tin welded to the back :)
 
JDM said:
Thanks for the replies guys. I have to say It does sound good.

I was thinking of removing the back box completely and just having a twin stainless section with new exit pipes (style to agree) in place of the box. Do you think this will be rediculously loud, bearing in mind that there is still the pre-cats and resonators in place? I just want a nice sound with some good bangs and pops, nothing that sounds like a sooped up corsa with a Heinz baked bean tin welded to the back :)

Strange - I can't get access to the clip :thumbsdown:

Glad the decats worked.
Removing the rear can will surely just make your ears bleed. People who fit some aftermarket boxes have to change them so nothing will I'm sure be unbearable.
 
As above, id usually say remove one or the other, but indeed the manifold cats and (tiny) resonators are indeed still there. If you do it, just make sure you have a nice cut to either sleeve or flange it back on if you don't like it!

Aghh want mine done so much!
 
Ed - my compromise was to fit a pair of the ///M rear boxes. If they can happily cope with a 3.2 revving to 8,000 then no issue with a 3.0 at 6,000 the resonator also went out of necessity.

I also to your point had everything flanged and appropriate hangers, so that at any time I could change to any aftermarket box or internally modded one with ease

DSC02755.jpg


JDM - would love to see a couple of shots of how your cat pipes now look and fit
 
Ed - I would ensure that I could easily refit the box or an after market one without any hassle. I'm unsure what to do at the minute and still like the thought of a quad, the more I look at the CJ's, the more I want it :D. Just don't want to be paying stupid money. I cant help thinking that all these mods Im doing / planning, It would make more sense to save the money and just buy an 'M'.

CJ - I have attached a couple of pics with the cats missing and then with one of the bypass pipes welded in.. Sorry, they are the only ones I managed to take and they don't look anything compared to your pic... That looks fantastic. I want it.. How much did it cost for the quad if you don't mind me asking?

img1210y.jpg


img1212d.jpg


img1211d.jpg


img1213b.jpg
 
CJ - That is one niiiice job... Not too sure about the boot 'mod' though to accommodate it, bit too hardcore for me! Im guessing you relocated/bought a smaller battery?
 
JDM - Neat looking job - thanks for the photos

Price for mine - I'm reluctant to say as you'll only get upset, but £300 for the beautiful stainless steel pipework, brackets, flanges and all. Supplied my own brand new ///M boxes that were £21 win on Ebay :) Took them 7 hours of 2 guys working but it was a pre agreed fixed price deal.

Ed - sure. I chopped the battery box in half and rebuilt it to take a race battery, while retaining all the crash protection cut off, etc. Bolted a plate in to cover the void. Few other bits and bobs needed sorting, heat shield adding, fume filter removing, and so on.

Came out like this:
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Cant watch the video, bummer :(

I thought most of the noise baffling was in the backbox? Im sure changing that would have had the same effect, no?
 
I know this is a bit of a resurrection, but I'd be interested in feed back from the above posted - particularly JDM who did this.

I am in the market for more noise for my E86 3.0si - which at present just doesn't give enough. Occasional pop and bang from exhaust when very hot, but that's it.

I was thinking about removing the secondary cats to add some more noise and keep standard back box, but JDM sounded underwhelmed above when he did this? Also I think new visual inspection for OEM cats at MOT time mean that although emissions test might be okay - the straight welded decat solution might be a non-starter. As such a flanged, and more expensive, system might be needed - but this starts to get more expensive, and I am concerned as to whether the rewards are worth it?

I have also been looking at back box solutions (as I understand this created a lot of back pressure on the Zed). I would ultimately combine this with the flanged decat solution and was thinking Remus or Eisenmann, but then we start to get seriously expensive - also with both, would that be too loud? Does anybody have a view on whether an M back box would have similar effect with flanged decat solution?

Sorry for the resurrection and ramble - but any help would be much appreciated.

Your quietly,
Alex
 
well im now thinking about having the lower 2 cats removed and having a cat back system fitted to the back along with an aftermarket can.

looking at these

http://www.mijexhaust.com/bmw-exhaust-system-stainless-steel-exhaust.html
 
MIJ are the guys that built the tube part of my system. Great work.

It's really important that you are clear about exactly what you want, else you'll end up with something too noisy, too quiet, etc.

I know someone else weht there and had the system removed as it didn't meet their needs.
 
Nova2k7 said:
well im now thinking about having the lower 2 cats removed and having a cat back system fitted to the back along with an aftermarket can.

looking at these

http://www.mijexhaust.com/bmw-exhaust-system-stainless-steel-exhaust.html


Have you considered whether you'll go for a flange system on the CAT removal given new MOT visual testing rules?
 
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