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Discussion Starter · #1 ·
I just recently ordered the CNT racing downpipe which is an OBX downpipe with a cat welded in. All of the images of the S60R's OBX downpipe online show a very strange flange where the dp attaches to the cat-back. From the pictures, it looks like the flanges will definitely not match up.

What I would assume is that all of the pictures online of the OBX pipe are generic photos of one of their other downpipes and that the flange will match my cat-back flange. I have spent a few days now searching forums and no one has ever reported having to customize the OBX flange to adapt to the stock cat-back so I assume I will have no problems but wanted to know if anyone could give me a definitive answer.

When I am done, I am going to do a pretty detailed write up of both the downpipe install/review and custom cat-back with sound clips and everything. It will look like the stock catback except the resonator section will be 3" instead of 2.25", the dual 2" will become dual 2.5" (which is equivalent to 3.5" round), and the tips will be 3" angle cut instead of 2.0" angle cut. The muffler will be deleted and the resonator replaced with a Dynomax bullet. To my knowledge no one has ever put a bullet on a Volvo so this should get interesting. Total cost of project including CNT racing downpipe, cat-back supplies, and cat-back labor will be around $650. Not bad considering an IPD downpipe+catback would run you $1800.
 

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Here's a shot of the flange on the OBX downpipe from the Kid's install thread:



Link to thread: http://forums.swedespeed.com/showthread.php?138910-The-Kids-OBX-DP-install

Here is an alternative view from Volvofla's install thread (he installed the OBX downpipe for the S60R on his XC90:



Link to thread: http://forums.swedespeed.com/showthread.php?164236-OBX-3-quot-Downpipe-for-XC90-2.5T

Long story short: the flange doesn't need to be modified to match up with the stock flange on the cat-back. However, you may find that the fitment of the OBX downpipe/CNT downpipe causes the flange to rub on the heatshield on the passenger side of the center tunnel.

Are you using stainless steel mandrel bent piping for the catback (and the stainless steel version of the bullet)?

Cheers,

Jeff
 

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Discussion Starter · #3 ·
Thanks a million for the help. I guess at certain angles it looks extremely odd. The piping is SS but the bullet is alumized steel. Didn't want to pay double for the SS and I figure if I have problems I can just swap them out. I don't plan on having my R forever tho so I should be ok.
 

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Discussion Starter · #4 ·
The uninstallation of my stock down pipe was a real PITA. Actually, it was such a PITA that I won't even go there right now.

I have to say, this CNT racing downpipe has really impressed me! It fits perfectly. It does not pull my catback towards the passenger side like OBX dps do. I have about 1/4" between the edge of the flange and the passenger side heat shield without even rounding the corner of the flange. All the welds look perfect and CNT even welds a name plate on the downpipe. Also, unlike the OBX downpipe, I did not have to trim the hanger bracket at all. Both hanger brackets were the EXACT perfect length. My only complaint is they ship it with the wrong size bolts, which to me is a little inexcusable but I just re-used my turbo bolts.

Also, in this thread post #12, someone talks about how braided is cheap and won't last long. I was surprised to see the CNT dp had the inner interlock design which according to that poster is the much better design.
http://forums.swedespeed.com/showthread.php?136218-OBX-downpipe-install-and-review.

If anyone wants to know anything about this dp just ask. I haven't had time to test it out yet because I am going straight into a catback install.

I am a very happy customer of CNT right now.
 

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Discussion Starter · #6 ·
The CNT downpipe seems new as of this year 2012. Below I have posted some pictures of the install. One of the more important photos is the one than has the toothbrush in it. It shows a good 1/4" gap between the flange and the heatshield on the passenger side. It is good to see I won't have to modify that like OBX owners do. I can see how the old cat could be considered a flow restriction. It is like 1mm x 1mm mesh. Like trying to suck water through a cloth. Click on any one of the photos to access my Flickr where more application photos are stored.

<a href="http://www.flickr.com/photos/saleen9090/7877638828/" title="IMG_3449 by Saleen9090, on Flickr"><img src="http://farm8.staticflickr.com/7112/7877638828_eff3ee60be.jpg" width="500" height="375" alt="IMG_3449"></a>

<a href="http://www.flickr.com/photos/saleen9090/7877636250/" title="IMG_3451 by Saleen9090, on Flickr"><img src="http://farm9.staticflickr.com/8301/7877636250_3015eddebe.jpg" width="500" height="375" alt="IMG_3451"></a>

<a href="http://www.flickr.com/photos/saleen9090/7877633998/" title="IMG_3458 by Saleen9090, on Flickr"><img src="http://farm9.staticflickr.com/8435/7877633998_71b1aa59a2.jpg" width="375" height="500" alt="IMG_3458"></a>

<a href="http://www.flickr.com/photos/saleen9090/7877633270/" title="IMG_3468 by Saleen9090, on Flickr"><img src="http://farm8.staticflickr.com/7273/7877633270_ab2d0396b1.jpg" width="500" height="375" alt="IMG_3468"></a>

<a href="http://www.flickr.com/photos/saleen9090/7877627770/" title="IMG_3482 by Saleen9090, on Flickr"><img src="http://farm9.staticflickr.com/8428/7877627770_2771cf35c4.jpg" width="500" height="375" alt="IMG_3482"></a>

<a href="http://www.flickr.com/photos/saleen9090/7877628672/" title="IMG_3479 by Saleen9090, on Flickr"><img src="http://farm9.staticflickr.com/8285/7877628672_5baa36e26a.jpg" width="500" height="375" alt="IMG_3479"></a>

<a href="http://www.flickr.com/photos/saleen9090/7877627184/" title="IMG_3483 by Saleen9090, on Flickr"><img src="http://farm9.staticflickr.com/8292/7877627184_19157b0a2b.jpg" width="500" height="375" alt="IMG_3483"></a>

<a href="http://www.flickr.com/photos/saleen9090/7877624974/" title="IMG_3487 by Saleen9090, on Flickr"><img src="http://farm8.staticflickr.com/7130/7877624974_bf6fba2561.jpg" width="500" height="375" alt="IMG_3487"></a>

<a href="http://www.flickr.com/photos/saleen9090/7877624304/" title="IMG_3488 by Saleen9090, on Flickr"><img src="http://farm9.staticflickr.com/8425/7877624304_4f9b12187c.jpg" width="500" height="375" alt="IMG_3488"></a>

<a href="http://www.flickr.com/photos/saleen9090/7877639476/" title="IMG_3509 by Saleen9090, on Flickr"><img src="http://farm9.staticflickr.com/8425/7877639476_9828ddd361.jpg" width="500" height="375" alt="IMG_3509"></a>
 

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I've had my CNT dp on for 6+ months now and I'm very happy with it. I'm also one of the many people that had trouble getting the OBX dp to fit properly and I resorted to heating it and bending it to pull it away from the under body of my car. I was skeptical about this CNT pipe at first but the seller assured me that they haven't had any fitment issues. Fitment was good and the price even better at half the cost of other options that include a cat.
 

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Discussion Starter · #9 ·
I've had my CNT dp on for 6+ months now and I'm very happy with it. I'm also one of the many people that had trouble getting the OBX dp to fit properly and I resorted to heating it and bending it to pull it away from the under body of my car. I was skeptical about this CNT pipe at first but the seller assured me that they haven't had any fitment issues. Fitment was good and the price even better at half the cost of other options that include a cat.
I have had mine now for 4 months with no issues. CEL free but I did use a spacer. My only complaint would be the odor. Not sure if it is because I am running a little rich with the DP or because some cats have an odor when new. Found this excerpt which explains it a little.

"As the fuel burns, the organic sulfur compounds break down into simpler compounds. If the engine is running lean (more air than is needed to burn the fuel), the sulfur is likely to be SO2, or sulfur dioxide. The catalytic converter can change this into SO3 (sulfur trioxide), which then reacts with the catalyst to form sulfates on the catalyst. Over several minutes there is a build up of sulfates. If the engine suddenly starts to run rich (not enough air to burn all the fuel), such as when you stop at a red light, climb a steep hill, or brake hard to slow down, the chemistry changes. Now the sulfates are unstable and they react to form hydrogen sulfide, which is expelled from the exhaust pipe all at once. The high concentration is the reason for the bad smell! This effect is a common problem with new vehicles because the catalyst is working at a very high efficiency. However, as the catalyst gets older, the activity drops. Fortunately for us, one of the first reactions to be affected is the formation of hydrogen sulfide. So as the catalyst gets older, the smell will go away. It should also be noted that many catalysts never smell bad. One reason might be because the vehicle doesn't run lean for much of the time, or perhaps the catalyst has an extra component that reduces the production of hydrogen sulfide.
 

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I have had mine now for 4 months with no issues. CEL free but I did use a spacer. My only complaint would be the odor. Not sure if it is because I am running a little rich with the DP or because some cats have an odor when new. Found this excerpt which explains it a little.
I don't get much of an odor with mine.. but then again I did switch from a catless OBX that stunk up the block if I left the car idling in my driveway for a few minutes.
 

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Thinking about pulling the trigger on this DP for my VR this coming pay day. Anybody else running this downpipe?
 

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i am... Very good DP. no complaints here.
 

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Discussion Starter · #14 ·
So going from stock DP to a CNT, how big of a difference was it? Spools twice as fast or no? Any power increase before tuning?
Most noticeable difference for me was the sound. You can definitely hear the turbo spool a bit more. I personally didn't notice much of a performance increase but my butt dyno is not as sensitive as some.
 

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Hows passing emissions with the race pipe. My concern is the car not passing
 

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does anybody live in virginia that's running this dp? passing emissions?
 

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it has a car.. you shouldn't have an issue with emissions.. just make sure you have a o2 spacer to prevent cel.
 

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yeah sorry I did mean cat.. lol. For my cnt I got a spacer from a link Saleen gave me. Worked perfectly.
 

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CNT Install

"esmith813 "..

Go for it. I've had my CNT on since March along with an IPD cat back. Runs a bit rich at times ( can smell it after a long idle ) but the sound is great and I've seen a nice performance increase too. No issues on the install, except for my mechanic telling me he didn't like the flange fit at the turbo end...but I told him to put the gaskets in and shut up! I see good boost too...around 12 to 15 from 3rd gear...but I'm too busy looking for cops to really honk on it. I also added a SNABB turbo intake and a new TCV. OH...and yes...you'll have to use a spacer on the front O2 to avoid those CEL's.
 
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