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Which Catted Downpipe should I get?


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Registered
2008 Forester XT Sport
Joined
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119 Posts
Discussion Starter #1
Well guys, I need some help on a decision for my next mod which is going to be a catted downpipe. I decided not to go with a catless dp because from what I read...there's a really bad smell and the fumes can get nauseous. I use it as a daily and I always got passengers riding with me. Plus I want to do my part in saving the environment for future Subie generations!:biggrin:

I've narrowed my choices to these:

1) Cobb catted DP (bellmouth)
2) ERZ catted DP (bellmouth)
3) Invidia catted DP (divorced)
4) Perrin catted DP (divorced)

Before you guys flame on me and say search the threads, I did...just needed some thoughts and opinions on these, I know alot of you guys are running one out the four on the list. I need to know the positives and negatives about these.

Here's some basic questions:

1) Does getting a bellmouth or divorced wastegate really make a big difference?
2) Is the cast iron flange better than the stainless steel one?
3) Should I heat wrap the DP?

Right now these are the mods I have on my '08 FXT:
-Stock turbo
-Custom installed SPT exhaust
-Blitz intake with the AEM dry carbon filter also have the Perrin Afta-MAF hose
-Cobb AP Version2 running Stage 1 with Cobb base map

Future upgrades:
-VF43 (I have it but not installed yet)
-STI top mount intercooler with Samco hoses(I have this set up but it's not installed yet)
-Grimmspeed Up pipe with ceramic thermal coating (about to be ordered)
-Grimmspeed Cross pipe with ceramic thermal coating (about to be ordered)
-Grimmspeed Boost Solenoid (about to order it)
-Turbo inlet hose (Perrin or Samco?)
-Perrin oil catch can (have it but not installed)
-Walbro fuel pump (have this but not installed)
-Bigger fuel injectors (don't know what to get yet)

The VF43 turbo needs to be sent out, apparently the previous owner said it had a bad oil seal causing it to smoke but he wasn't too sure. The turbo had less than 15k miles on it with very minimal shaft play, the turbo looks extremely clean and doesn't look like he abused it. So if there's any local shops in Jersey or a place I can send it to, let me know. This is what I am planning to do with it: a new oil seal, port and polish, and possibly put a larger wastegate flapper with bigger opening. I don't think I'll be running an external wastegate on my set up.

Well there you go guys...let the opinions fly!:rock:
 

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Premium Member
2004 FSTI automatic
Joined
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2,659 Posts
With this many variables, you will get all sorts of opinions...and IMO opinions are like kittens, and should be given away.

First, talk to your tuner...as most of them have preferences when tuning intakes,ebcs, and injectors. Go to your regional sub-forum for tuner suggestions.

I dont know about the SPT exhaust, but I am guessing it is 2.5". If so, Cobb dp is prolly your best choice. If you want a 3" dp, Helix (bellmouth) is a solid choice. Wrapping is good, but not the cat.

If doing a Xpipe, might as well do p&p elbows as well.

Hope this helps.
 

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Registered
04 FXT, 61 Stude
Joined
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1,742 Posts
The SPT is a 3" setup that has the donut style flange for the stock DP, which is why I voted for the COBB catted DP. Out of all those I've heard (I'm still running a stock DP :icon_frown:) that the COBB is the way to go. But that's just my $.02.
 

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Premium Member
2017 VW Golf SportWagen 5MT
Joined
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10,887 Posts
Are you buying these used or new? Prices would be a factor for my vote.

I'm happy with my catted Cobb. Mine was used, I'm not sure if the new ones are made in the same factory. Local shop recommends Invidia. Cast iron bellmouth -- just a guess, but it could quiet things down a bit. I would not wrap any parts of the downpipe, Cobb does not suggest it so I don't think it's needed. Also, some downpipes have the cat on the midpipe end (Cobb) and some are closer to the bellmouth -- I'd rather have the cat closer to the midpipe, further away from the engine bay.

Stan
 

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The Sub kit guy
2005 Forester X & XT VF39
Joined
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13,100 Posts
The Cobb piece is tough to beat quality wise. I spent $300 on a used Catted Cobb DP. I also liked the fact it had a donut flange so I could keep my stock midpipe/STi muffler and keep the noise down.

Don't forget you will need some sort of engine management when you do the swap.
 

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Registered
2005 Forester XT 4EAT
Joined
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2,185 Posts
All i can say is the Divorced wastegate in theory seems like a better design, but the differences are probably negligable.

Also definatley wrap your downpipe, i made the mistake of not wrapping mine and my turbo during the install and they both throw a ton of heat into the engine bay.
 

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Registered
2014 Forester XT Touring CVT
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800 Posts
i say Cobb DP... just installed mine this past weekend.. sounds puurrrrty.. n the gain was more than i expected..

n yes dont forget the EM
 

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Registered
2007 Sports XT 4EAT
Joined
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2,501 Posts
I had voted ERZ since it's cheap, but I just saw that reviews on NASIOC/IWSTI are a little bit mixed on fitment/build quality of the catted version, so maybe that's not a good route.

The best bet is to go used. There are lots of quality options out there, so it's not hard to find a good deal on a used DP.
 

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Registered
04 SOLD!
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943 Posts
The VF43 turbo needs to be sent out, apparently the previous owner said it had a bad oil seal causing it to smoke but he wasn't too sure. So if there's any local shops in Jersey or a place I can send it to, let me know.
Hate to break the news, your VF43 is a paperweight right now....VF series turbos aren't rebuildable..

I'd go with the Cobb DP btw.
 

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Registered
2008 Forester XT Sport
Joined
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119 Posts
Discussion Starter #11
Don't forget you will need some sort of engine management when you do the swap.
Got the Cobb AP...probably will get a custom map done...

Hate to break the news, your VF43 is a paperweight right now....VF series turbos aren't rebuildable..
DANG! For Real?!?! I thought the oil seal could be easily replaced by a reputable shop???

Are you buying these used or new? Prices would be a factor for my vote.

Stan
Well most of the parts will be new... tho I'm always looking for deals on here, Nasioc, e-bay and online stores...

Thanks guys for your advices and opinions....:icon_wink:

anymore opinions and advices are welcomed....
 

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Harbor Fright
2005 XT
Joined
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368 Posts
Another DP option is ceramic coating- I have a coated Stromung divorced shorty (from MadDad) that reduced the engine bay heat by a very substantial amount.

Another plus (especially here in the snowbelt) is that the coated DP has held up through four winters now and is still in great shape.

Also recently added a GrimmSpeed coated UP, which reduced the under-hood heat even more.
 

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Registered
2008 Forester XT Sport
Joined
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119 Posts
Discussion Starter #14
Yeah missed that.....VF43 with blown seal = bummer.
Well can't i send the turbo to Blouch Turbo Inc.? :icon_question: I heard they do turbo rebuilds... but i haven't had the chance to contact them yet...

FXT22 - from the other forums, people said i could heat wrap the pipe but not the cat itself...is that true?
 

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Harbor Fright
2005 XT
Joined
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368 Posts
FXT22 - from the other forums said:
Can't honestly respond to that as I have no experience with wrapping, but I stand by my original reply regarding coating in this climate...
 
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