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2004 Forester XT
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Discussion Starter #1
Hivemind, I'm looking for some advice.

To wrap up my engine performance modifications I would like to get a cold(er) air intake and a cat-back exhaust. There are about one billion options so I want to provide some further information to help narrow some focus.

I have a 2004 XT 5spd, and about a year and a half ago I re-built my engine from a brand new short block and along the way bolted on a few upgrades and modifications. The car currently runs fine, surges a bit when its cold, but I know this is because I'm driving on an unfinished setup, and have yet to get a pro tune. Here's what we have:

- Stock air intake
- Stock turbo inlet
- BNR Evo 3 16G turbo
- 2006-8 (I think?) OEM STI intercooler
- Stock fuel pump
- Stock injectors (I have a box of Deatschwerks 740s I'm going to install)
- Stock headers
- Invidia cat-less up-pipe
- Cobb bellmouth down-pipe
- Stock cat-back exhaust
- Running out of the box Cobb Accessport Stage 2 map

So, what I'm looking for are recommendations regarding the cold air intake and cat-back system

Things I think I know (but could be wrong about):

- The actual intake makes little difference. There could be legitimate differences between the shorter intakes that pull from the engine bay, which would also require a heat shield to be effective. There are also longer ones that snake down into the wheel well. These could be a pain to deal with when it comes to cleaning the filter; they're also around $100 more.

- The stock cat-back system on the XT is actually pretty good and replacing it is really just for a few more HP and some added noise. I think I want a little more rumble. Like everyone else, I want that goldilocks zone, it seems like the Invidia pipes are super loud, and if for nothing else than aesthetics, the stock system is just too gosh-darn quiet.

What I'm looking for are insights regarding fit, quality of product, "If I could do it again..." responses.

Thanks for reading!
 

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2008 Forester XT 5-Speed Manual
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CAI: (almost) every CAI intake modification I have ever seen on an sg forester has been a mistake (including my own, which I uninstalled). With very few exceptions this is a bad idea. Nobody makes a CAI for (SG Foresters) that properly insulates the intake from the hot air and radiant heat in the engine bay. Unless you fabricate a box for your cold-air intake that effectively isolates your intake such that it is UNABLE to collect hot air from the engine compartment and ONLY sucks up cold air through the fender etc ... you will be increasing your IAT, which is the exact opposite from what you want to do. People like CAI's because:

- they are a cheap mod, and everyone likes that +10hp placebo effect.
- they sound cool.

But unless you go to the length of full-on custom fabrication to isolate the intake what you are actually installing is a hot-air intake.

EDIT: apparently Grimmspeed now makes a CAI that is suitable for SG foresters.
 

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2004 Forester XT Auto
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236 Posts
I agree with Tinman on the usefulness of "CAIs", while they can be done well, intakes on these cars aren't a restriction until you start making big power. If you want more intake noise, delete the snorkus assembly and keep the factory air box. Also keep in mind any changes to the MAF tube (shape, size, finish, ANYTHING) WILL NEED A TUNE to prevent a lean condition.

As for catback, I currently have an SPT axleback that I really like the sound of, with a catless down and midpipe it ought to be just about perfect volume.

Unrelated to your questions, but you NEED to upgrade your fuel pump ASAP. The stock pump will support the stock tune and parts....but that's about it. A walbro GSS342 is around $50 on amazon, super easy to install and supports 350+ HP. Also if you don't already have them, get AFR/wideband and boost gauges so you can see how poorly that cobb map is running. One more thing to keep in mind, those injectors will not run without a tune.
 

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02 WRX
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I'm going to assume you two haven't seen this yet then: https://www.grimmspeed.com/cold-air-intake-02-07-wrx-sti-04-08-forester-xt/

There is a ton of information on that page, and a couple videos that show it installed and at the dyno. This intake is something I've been testing for a long time now, but it has only been available for a few weeks. Make sure to take a look at it. The main point i wanted to drive home is that while cold air is important with an intake, the decrease in restriction is arguably more important. And all too often you'll see someone write that you don't need an intake until XXX power level. However, that is usually misconstrued where it is based off of where the airflow will run out of voltage on the sensor. Traditionally that refers to when you need a LARGER MAF diameter, not to where an intake becomes effective. Here we once again show that even on low output cars and stock turbos that the decrease in restriction from the intake results in additional boost in higher RPMs where our relatively small stock turbos will fall off.

Also, you'll see this intake is very different from the ones that have been previously released for this chassis.

Chase
Engineering
 

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Nope! Hadn’t seen that! I saw a post some time back where you guys had been planning to create a CAI that is compatible with SG foresters. I checked your site awhile ago for it but didn’t see anything and assumed the project was abandoned.

Edited: shut up and take my money :p will post a write up once it arrives and is installed.
 

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2004 Forester XT
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Discussion Starter #6
Thanks for the info on the fuel pump!

I know the vehicle won't run on the new injectors, but because I'm doing it myself my tuner is sending me a "get you to the shop" map.
 

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Discussion Starter #8
I agree with Tinman on the usefulness of "CAIs", while they can be done well, intakes on these cars aren't a restriction until you start making big power. If you want more intake noise, delete the snorkus assembly and keep the factory air box. Also keep in mind any changes to the MAF tube (shape, size, finish, ANYTHING) WILL NEED A TUNE to prevent a lean condition.

As for catback, I currently have an SPT axleback that I really like the sound of, with a catless down and midpipe it ought to be just about perfect volume.

Unrelated to your questions, but you NEED to upgrade your fuel pump ASAP. The stock pump will support the stock tune and parts....but that's about it. A walbro GSS342 is around $50 on amazon, super easy to install and supports 350+ HP. Also if you don't already have them, get AFR/wideband and boost gauges so you can see how poorly that cobb map is running. One more thing to keep in mind, those injectors will not run without a tune.
I took a quick look on Amazon and found two kits, one in the $80 range with an "install" kit and one in the $50 range that looks like just the pump. What's your experience with the install? Do I need the "kit"?
 

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02 WRX
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Nope! Hadn’t seen that! I saw a post some time back where you guys had been planning to create a CAI that is compatible with SG foresters. I checked your site awhile ago for it but didn’t see anything and assumed the project was abandoned.

Edited: shut up and take my money :p will post a write up once it arrives and is installed.
Excellent Tim, thank you very much! I apologize for no installed pictures being on the page itself, but I am having that fixed right now. I've been running the prototype for nearly two years now, it is really just a situation where other projects needed to be completed first. Please let me know if you have any questions about it as I know a thing or two about it :p

What considerations would I need to make regarding my MAF with the product?
With the intake? I would say you just need to get it tuned at the same time you do any other tuning. On a lightly modified car I have had no issues running it with just an OTS map for a stock intake, but I do also know that it is not optimized or ideal. Runs fine, but I know it is fat at WOT and that is leaving a lot of power on the table. I address in the video about why you should ALWAYS get a tune with an intake, but the gist of it is mainly: Even if the AFRs look fine it isnt guaranteed that your load values are right, and thus the ECU is not necessarily looking up the right values for timing. Additionally the decrease in restriction will directly result in more boost, and you don't want something like that unaccounted for, especially up top when the margin for error shrinks.

Chase
Engineering
 

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No, you can just reuse your OEM strainer and the pump is a direct swap. Just need to be careful when removing the strainer from the old pump, since it's held on by a small plastic tab and a tiny one-way washer. There's a great fuel pump swap writeup on on scoobymods, it's for a WRX but FXT's are very similar. Do note that you do not need to remove the seats at all...wish I would've realized that sooner rather than later.

Edit: Didn't answer your question! You don't need the kit, in fact the strainer it comes with is smaller than OEM.
 

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@GrimmSpeed How well does this fit on an XT? Cobbs SRI which I have not only has that HUGE hole in the front, but the fitmet in general for the FXT is lacking. For instance, my maf and after maf hose do not fit well and are at an odd angle which seems fairly common. Do you guys by chance have any fitment photos from an FXT?
 

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02 WRX
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@GrimmSpeed How well does this fit on an XT? Cobbs SRI which I have not only has that HUGE hole in the front, but the fitmet in general for the FXT is lacking. For instance, my maf and after maf hose do not fit well and are at an odd angle which seems fairly common. Do you guys by chance have any fitment photos from an FXT?
I actually don't think that we have any pictures posted online of this on an FXT unfortunately. However, with that said: unlike most intakes for this platform, this intake was designed initially on an FXT, and then adapted to fit the different years of WRX. This adaptation was mainly in massaging the front edge where the core support is in order to fit the various "eyes" of the WRXs. So in my opinion the fit for FXT is fantastic, as I was well aware of the fitment issues of other intakes which seem to be 100% designed for the WRX and just so happen to fit well enough on the FXT to call it a confirmed fitment.

My personal car is an 04 FXT, and we have two employees here with the same car. And if I'm not happy with the way something fits or preforms, it doesn't get released.

Chase
Engineering
 

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I actually don't think that we have any pictures posted online of this on an FXT unfortunately. However, with that said: unlike most intakes for this platform, this intake was designed initially on an FXT, and then adapted to fit the different years of WRX. This adaptation was mainly in massaging the front edge where the core support is in order to fit the various "eyes" of the WRXs. So in my opinion the fit for FXT is fantastic, as I was well aware of the fitment issues of other intakes which seem to be 100% designed for the WRX and just so happen to fit well enough on the FXT to call it a confirmed fitment.

My personal car is an 04 FXT, and we have two employees here with the same car. And if I'm not happy with the way something fits or preforms, it doesn't get released.

Chase
Engineering
Thank you for the info (and sorry OP for hijacking your thread). I'll definitively be looking into this!
 
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