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11 sec club
04 Cayenne TT
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1,486 Posts
Discussion Starter #1
Stay tuned as pics will be included late tonight.

I got the Cobb TBE bolted on last night. My Draw Tite hitch is not user friendly with hangers so it looks like I'll be modding a small piece on it where the outboard hanger goes.

Other than that, it fits great. My initial opinion is that the TXS DP has the Cobb unit beat for flow. And the Cobb TBE is louder everywhere than the TXS stealthback/STi axleback setup. I'd say this is my limit on noise.
 

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05 XTi FMIC
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2,564 Posts
Sooo.....your happy with the COBB? :confused:
 

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261 Posts
Currently I'm looking for a DP that will mate to the stock catback as my wife says absolutely no loud exhaust. I even had a STI for a week or so, and she still noticed. So here are my questions:

1) Should I even bother trying to go stage 2 if I have to keep the stock exhaust?

2) When only comparing the downpipe (Cobb vs TXS), which is quieter?

3) Will the TXS fit the stock catback?

4) Should I consider the Helix one?

Thanks
 

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Premium Member
2004 Forester XT
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815 Posts
A downpipe will only increase sound minimally on a stock catback. I say buy a downpipe, keep your stock catback to keep the noise down, and switch to your stage 2.
 

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Aspiring Post Ho
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267 Posts
You will hear a little more turbo spooling noise but it is more like a whistling. Yes, the TXS stealth back will work with the stock axle back. If you wanted to use your your stock cat back you would have to get the TXS dp and their race pipe (no cat) that is made to use with any cat back. I am not sure if it will bolt up to a stock cat back though. IMO, even though I am running the TXS set up, I would not run it unless you were going to go all the way back to the axle as you may just be setting yourself up for headaches trying to find something to work right.
 

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11 sec club
04 Cayenne TT
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1,486 Posts
Discussion Starter #6
GatorXT said:
Sooo.....your happy with the COBB? :confused:
Very.
I can walk up to the car and not see daylight in between the exhaust tubing and the lower part of the body. Or the O2 sensor wire stretched out in mid-air.
 

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11 sec club
04 Cayenne TT
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1,486 Posts
Discussion Starter #7
Ok here's some comparison pics. The bellmouths show the TXS is much bigger and generally centered on the turbo instead of the turbine outlet. The height difference on the two leaning against the freezer is almost correct but the TXS is drooping a little. This would be the difference in how much lower the TXS hangs than the Cobb. Another difference between the two is that the TXS is all one piece and doesn't have the lip on the pipe after the bellmouth is welded on in the interior like the Cobb does.



 

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11 sec club
04 Cayenne TT
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1,486 Posts
Discussion Starter #8
OK here's more of the downpipes as they move to the catalytic converter(s).





 

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11 sec club
04 Cayenne TT
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1,486 Posts
Discussion Starter #9
And here's the two cats. The Cobb one is significantly smaller in both length and cross section. The larger cat slows the flow down as the cross section increases in diameter (area) to help give the exhaust gas time to react with the catalyzing matrix. And then there is another big difference between the two - the end of the catalytic converter with the Cobb necking down to accomodate the stock exhaust.



 

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11 sec club
04 Cayenne TT
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1,486 Posts
Discussion Starter #10
Moving down to the intermediate pipe. Other than the ends, not much else. But you can notice that the Cobb's mounting tab doesn't hang the pipe down as low as the TXS. I took the pics with the two pipes in the orientation they would be installed.

Inlet




outlet
 

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11 sec club
04 Cayenne TT
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1,486 Posts
Discussion Starter #11
And finally a couple of muffler pics. This is a STi muffler compared to the FXT specific Cobb one.



 

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11 sec club
04 Cayenne TT
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1,486 Posts
Discussion Starter #12
After spending a couple of days of driving on the normal commute I can only comment on aesthetics until I get a chance to hit the dragstrip. But even then I'm running the stock FXT IC until I get the APS unit in (I had to trade the WRX one I had plus a few bucks) so it might not be apples to apples.

Anyway, as mentioned before the TXS/STi combo lives up to its accolades as being a very stealthy combination. The Cobb isn't going to let me sneak up on anyone. But it's not all that bad. I just started listening to the radio again since I was trying to see if I could hear any rattles and also get used to the sound. The Cobb is noticeably louder at idle and at low speeds when driving around until the road noise drowns most of it out. Of course punching it is also noisier, but the overall volume is less than I expected. My commute consists of 50mph and slower roads so I don't get much opportunity to open it up with traffic and all.

I can still hear the wastegate flutter. It sounds less high pitched but I think it's just as loud with the TXS.

Ground clearance is a lot better. It was raining on the day I swapped out the exhaust so I had to do it in the garage so there are no pics of the TXS installed to compare the two. Walking up to the car from the side, the exhaust looks stock underneath. The muffler is noticeable in that it's polished. I may clean the tip but the rest of it I'm going to let get dirty to help dull it a bit.

The O2 sensor location is closer to the front of the car on the Cobb. I can now use the stock harness clamps/clips to keep in in place. The TXS required me to remove the clips and stretch out the harness to the point that it was basically just hanging in the air to get to the mounting location. Seeing as how this harness is yellow, it was really noticeable from the driver's side of the car from underneath (or just walking up to it). I had to get some plastic wire wrap in black just to try and hide it. Maybe this is an 06 thing (?)

I definitey like the tip since it extends more than the STi. But I didn't have any clearance issues with the STi, even with a hitch. But for both mufflers I had to use long hangers and bend at least one mount to get it right. The Draw Tite hitch I have doesn't let the outboard hanger extend past the stock location as the metal bends inward so that it cannot hang straight down. I guess a pic would show this best...

So all in all, I'm happy with it. It looks better on the car to me. I don't plan on building a 400whp beast or anything so I just don't see a huge loss (if any after comparing the cats) for what I'm planning to do.

Both systems were the same ease/difficulty to install.
 

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Premium Member
2004 FXTi
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763 Posts
One thing to keep in mind is that there is a large difference between not only cat size but also what is inside the cat. Typically the larger cats are a ceramic brick and tend to break up more quickly. The smaller cat is typically a metal matrix cat and can actually flow more despite being smaller and has a longer life expectancy.

But all in all it is more about sound preference than any significant power difference. And the best bang for the buck is anything purchased used from some kid that goes through exhausts faster than I go through titey whiteys :biggrin:

Regards,
Justin Wade
2004 FXTi
 

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Premium Member
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2 Posts
I would appreciate a picture of how the exhaust mates up with your trailer hitch and maybe a more detailed description of the bending involved. Thanks.
 

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Aspiring Post Ho
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267 Posts
Cool so when my larger cat breaks down it should flow alot more air than the small one! Outstanding. I will look at it as a break in period. I think that is a plus for the TXS set up then!
 

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11 sec club
04 Cayenne TT
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1,486 Posts
Discussion Starter #16
wadejg said:
One thing to keep in mind is that there is a large difference between not only cat size but also what is inside the cat. Typically the larger cats are a ceramic brick and tend to break up more quickly. The smaller cat is typically a metal matrix cat and can actually flow more despite being smaller and has a longer life expectancy.
Who knows for sure between these two what the difference is in flow. I don't think the TXS (looks like a Magnaflow) cat gives up anything in flow, per se, to the Cobb metal one. They're just different.
 

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Aspiring Post Ho
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267 Posts
TXS does use Magnaflow's for their cats. I watched them take one right off the shelf and weld up both ends to it when they made a new one for me to get the angles right so that it did not hang down like the first one I got.
 

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K.I.T.T. meet A.L.I.C.E.
2008 Forester XT 4EAT
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837 Posts
slightley o/t question, but the COBB Catback for the forester, is it the same as the one for the STI?
 

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2005 FXT/AT
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46 Posts
I have a Cobb Turbo Back with a trailer hitch on my '05 FXT. I used Kart-Boy long urethane exhaust hangers. It takes care of the COBB exhaust banging on the trailer hitch and looks nice. For the mid-pipe you can use a long Kart-Boy or the OEM hanger.
 
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