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Discussion Starter #1
Ok - while I know there are folks out there with issues and problems, I want to get some thoughts on questions regarding this. I installed a catless CPE DP.

For the record - hated the install as others have mentioned and fully agree on every point. This is very unlike previous DP installs like my Subaru and Evo. Which takes no time at all and you can easily check for leaks at the turbine exhaust to DP connection with your hand.

I believe I may have a leak at the turbine housing/DP connection. When removing/separating the stock pipe, the top nut came off, while the lower one did not and the entire stud pulled out. I've read this is a thing with some installs :( The nut would not remove from the stud without going to a point of possibly destroying the stud (not a good idea if you don't have another on hand). So when putting everything back together, we (friend and I) crossed our fingers as we tightened the top nut and lower stud with nut back into place.
What torque spec to use...well in this case we went German > Gudentite! Because it was going to be difficult to get a good enough hit with a torque wrench in that area without some specialty connectors to torque it right.
Quick soapbox > GD it as it seems like this car rusts about everywhere with little miles on it (I live in the PNW - feel for you guys on the East Coast). Those exhaust nuts were covered in rust...not as horrible as the driveshafts (that is about ridiculous) but still...every where I look at this 2yr old car (MY2018 with 15k) there is rust happening everywhere! Soapbox collapsed

Here come the questions to those that have successfully installed their catless DPs with no leaks:

Do you hear the turbo a lot - e.g. whistle a lot more even though you are barely into any boost? I am definitely hearing it a lot more than ever before, however I think this could be because of the thickness on the stainless used on the new DP compared to stock, of course having no cat (which can be a bit of a silencer), and lastly the turbo and DP being right there against the firewall. I think this is either the case (like a subaru who also has the turbo and DP near the firewall) or I have a leak and this clearly did not seal.

What is the best way to test for a leak in this situation? Unfortunately I do not have access to a smoke machine, so that is out (otherwise this could help a lot). It's in such a bad spot you can't simply spray some window cleaner (the kind with meth that bubbles up) or put your hand around it to check for leaks.

SIDE NOTES : I would recommend to have on hand as cheap insurance when doing this install >
1) stud or two in case you happen to run into the same as I and some others have (PN#W712458 S900)
2) an exhaust nut or two because of #1 (PN#W520103 S442)
3) possibly a new DP gasket (if the other comes out in bad shape - however mine looked ok to reuse) (PN#EJ7Z 6L612 A)
4) copper hi temp antiseize (over the gray)...$10 at the autoparts store will last you forever
5) a new DP to catback gasket/clamp just in case (I replaced my original factory when I did the catback and successfully reused that one with no leaks...still had one on hand just in case) (PN# is on the forum but I bought my 2 from Cobb at much cheaper price)
6) lots of patience (can't remember the PN for that one and they were out of stock when I looked)
7) There was one last thing but I'm forgetting it and will add later if remembered.

Anyway - that's all for now. Thanks for any thoughts you may have.
 

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TL;DR

mine leaked too. replace the gasket. Can’t find a photo but mine blew out right after install. And yes one of the entire studs came out on mine too
 

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You can stand over the open engine bay to smell for exhaust gas or use an automotive stethoscope near the downpipe joint if you suspect a small leak.
 

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Discussion Starter #4
I have a small camera inspection tool (like a borescope), but I do not have one of those automotive ears...that would be good too.

I originally tried to smell for exhaust, but maybe the car was too warm and I need to do it more cold when its really rich. Just don't want to mistake it and pull it out for nothing.

What I meant above by hearing the turbo whistle so easily - if either of you have no leaks now (and catless?), do you still hear turbo whistle with not being in hardly any boost?
 

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I'm catless and I constantly hear the turbo whistling off boost. The sound eases up a bit after reaching a steady speed but is still slightly audible. I haven't checked for leaks under the car, but I did check the turbo/downpipe connection with a small mirror and it's not leaking. I'm confident the downpipe/catback isn't leaking either since I put a new gasket/clamp on when I installed it.
 

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With a catless downpipe you can EASILY hear the turbo spooling in part throttle. I actually took a low quality vid long ago, this was right after install when I suspected a minor leak


And here was a few day’s later after I fixed the leak. Listen to when I start to rev the engine, you can still clearly hear the turbo whistle

 

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Discussion Starter #7
I'm catless and I constantly hear the turbo whistling off boost. The sound eases up a bit after reaching a steady speed but is still slightly audible. I haven't checked for leaks under the car, but I did check the turbo/downpipe connection with a small mirror and it's not leaking. I'm confident the downpipe/catback isn't leaking either since I put a new gasket/clamp on when I installed it.
Before you went catless you didn't hear it like you do now right?

I mean, like you I could have this all sealed up and there is nothing wrong, but because I'm hearing it so easily now over before when just a little boost is being made (top it with the issues I had) I suspect I could have a possible leak.

I agree with you under a constant/steady speed I'm not hearing it much.
 

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Discussion Starter #8
With a catless downpipe you can EASILY hear the turbo spooling in part throttle. I actually took a low quality vid long ago, this was right after install when I suspected a minor leak

And here was a few day’s later after I fixed the leak. Listen to when I start to rev the engine, you can still clearly hear the turbo whistle
The whistle I'm hearing is more in the cabin/front of the car near the firewall where the turbo is. Do you hear that as well?
 

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Discussion Starter #10
I don’t know how else to say it man. If you think you have a leak, then you have a leak
It’s just a question asked - if you read my post (tldr), the Subaru has a similar sound because of the difference in the thickness in the oem DP vs aftermarket and opening it up more. Also add the turbo being close to the firewall you will tend to get more sounds in the cabin.

Ideally I was checking with others (and yourself) if this is the norm or not.
I will still get in there to do my best to check.

Don’t get me wrong, while I appreciate the input - don’t have to make it like its a PITA to answer or like I’m bothering the community.
 

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Before you went catless you didn't hear it like you do now right?
No, I did not hear it prior, the difference is large. The turbo spool reminded me of a diesel at first.

I'm only now remembering that I have the muffler bypass done and the turbo is much louder when the valve is open. It is still there with the valve closed, but muffled. If yours does not sound muffled a bit, check for leaks.
 

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Discussion Starter #12
No, I did not hear it prior, the difference is large. The turbo spool reminded me of a diesel at first.

I'm only now remembering that I have the muffler bypass done and the turbo is much louder when the valve is open. It is still there with the valve closed, but muffled. If yours does not sound muffled a bit, check for leaks.
Thanks for the response. In the cabin it does sound a little bit like a diesel turbo whistle. Drove it again and it seems to be loud in the 2/2.5k rpm and then dies off a little more (but the exhaust is much louder now, so that could be muffling it about those rpms).

First check over the weekend (smelling for exhaust on cold startup) got me nothing. I could smell zero exhaust fumes. Next I will try to get the borescope camera in there.

Crazy how other noises you may have never scrutinized after changing something out start making you think all kinds of things.
As I was attempting to get my head over the back of the motor there is a pretty good ticking sound that I never thought I heard before. Sounds like lash adjuster ticks in 1g/2g Mitsubishi 4g63's. With the hood closed its very hard to hear and it's not heard in the cabin. Guess I'll need to ID that too and check it off my list.
 

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I just installed a catless dp last weekend. You can get a torque wrench in there from the top with straight extensions. Torque is 35 ftlb for the turbo flange. After my install the car sounds just like all have described theirs sounding. Way louder and earlier spool sound, also louder overall exhaust volume imo. If you have a leak it will be loud as h#ll under the hood or right below the front chairs. Like the sound from behind the car or louder with a straight pipe. Good luck 😉
 

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Discussion Starter #15
I just installed a catless dp last weekend. You can get a torque wrench in there from the top with straight extensions. Torque is 35 ftlb for the turbo flange. After my install the car sounds just like all have described theirs sounding. Way louder and earlier spool sound, also louder overall exhaust volume imo. If you have a leak it will be loud as h#ll under the hood or right below the front chairs. Like the sound from behind the car or louder with a straight pipe. Good luck 😉
Thanks for the info - haven’t been able to dig back into it too much since last weekend.
I can attest that it’s not loud exhaust sounds under the hood or in the cabin. My biggest concern was thinking I had a small leak (not major) because of how I could hear the turbo whistle in the cabin so easily at the 2-3k range (otherwise the exhaust out the back is so loud you can’t hear any other noises above that rpm).

Side note: Curious how much quieter this would be with a high-flow cat DP (I have an AWE Track CBE). While I’m ok with loud, this is a whole new level of loud.
 
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