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Old 11-29-2014, 06:03 PM   #1
Tectonic
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Default TurboXS downpipe troublesome noise

I just got my heat wrapped, catted TurboXS downpipe installed today on my '14 hatch WRX, and tuned to COBB stage 2 (downpipe is only modification). After debugging a small leak I went for a spin through the neighborhood and then the freeway. Everything was fine, until I got off the freeway. After about 40 miles of freeway driving I came to a stop, started in 1st, and then when I depressed the clutch to shift to second there was a LOUD droning noise coming from the downpipe area (like a very loud engine lugging sound). It sounded exactly like someone trying to play my downpipe like it was a trombone. I did notice the lugging sound whenever I would let off the throttle on the freeway, but it was quiet enough to seem normal with a new DP. Any thoughts? Everything I have read about TXS DP's states that they do add a little noise, but this is different.

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Old 11-29-2014, 09:21 PM   #2
El Wray
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You did the two piece? I had issues with their supplied 'S' brace that secures the DP to the car chassis. The brace would keep breaking and would cause an annoying exhaust rattle. If not that, you'll probably want to make sure nothing came loose or hitting anything else.
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Old 11-29-2014, 10:26 PM   #3
Tectonic
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Yeah it's the two piece. I had some fitment issues getting the DP bracket on the hanger, but nothing appears to be broken. The noise isn't so much a rattle as a rumble. It correlates directly to RPM and is most pronounced between 1st and 2nd gear (when vehicle is warm) and the RPM decelerate. You can feel the rumble as it occurs. I'll take off the heat shield tomorrow and inspect the DP to turbo better
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Old 11-30-2014, 12:29 AM   #4
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With your description, sound like an exhaust leak. Maybe a bolt or two rattled loose. a couple bolts on the downpipe are difficult to get tight...really need to work those last few 1/12 turns of the wrench.

Also, if the DP is your only mod, why are you not on stg 1?
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Old 11-30-2014, 08:50 AM   #5
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boost-o-matic: I think you're right, I'll get back on those bolts and crank.

I'm running a COBB AP stage 2 that only requires a DP. It states that in the map description, and clearly says stock air intake and everything else. What are your thoughts on that? Thanks
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Old 11-30-2014, 05:02 PM   #6
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Sure enough, lost a nut on the underside of the downpipe/turbo mating. That certainly solved the main problem. Now I'm getting a heavy vibration w/noise. I can consistently replicate it when accelerating in 1st or 2nd and letting off the throttle to allow the engine to brake. Sometimes I can hear a tinny sheet metal noise associated with it, so I'm almost certain it's the extra O2 bung plug hitting the sheet metal above the exhaust.

Fitment Issues
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Old 11-30-2014, 09:53 PM   #7
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OK everything is resolved. To wrap this thread up:

The heavy vibration was caused by the downpipe rubbing against the sheet metal shield that separates the downpipe from the drive shaft. The extra O2 bung plug at the end of the downpipe near the cat is what was rubbing. I ended up modifying the sheet metal with a Dremel to eliminate the problem, and it worked.

This issue is all due to the poor fitment of the DP on the DP hanger. The hanger needs to be bent, or extended because the DP wants to hang just a bit lower. Another consequence of the DP riding a bit higher is that the O2 sensor (which is vertical) ends up even closer to the drive shaft! The sleeve on mine was worn through, so I had to zip tie it out of the way.
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Old 12-04-2014, 11:34 AM   #8
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Glad to hear there was a copacetic solution. Of all the downpipes I've owned (Cobb, CNT, Invidia, TXS) - the TXS felt much better on the butt dyno than the rest. Ended up replacing it due to some catback issues.
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Old 12-04-2014, 09:19 PM   #9
Tectonic
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Quote:
Originally Posted by El Wray View Post
Glad to hear there was a copacetic solution. Of all the downpipes I've owned (Cobb, CNT, Invidia, TXS) - the TXS felt much better on the butt dyno than the rest. Ended up replacing it due to some catback issues.
That's quite a few DP's. Glad to hear you liked your TXS

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Old 10-22-2017, 12:11 AM   #10
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I just installed mine and I'm getting a similar noise, and I want to run my wideband sensor but I don't know if it's possible after I drill out the heatsheild because the driveshaft is directly above!
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