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2004 FXT 5MT
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1,142 Posts
Discussion Starter #1
Looking for anyone that has installed the APS CAI on an 04/05 XT.

How hard was it to push the pipe through the fender hole? I read sirwilliams thread and it was a big PITA on his car, but I also read over on IWSTI that 06/07 STis had more trouble than the 04/05 ones since the fender hole got smaller for the newer model.

So I'm wondering if that's the case for us XTs as well.
 

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05 FXT
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1,540 Posts
I put a 70mm on my '05 and it's really snug, but it works. Bad part, it's so snug that it causes a popping noise whenever the engine rocks and has warped the panel a smidge. But it does fit. Ideally I'd enlarge ever so little and then spray it to keep the rust at bay.
 

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2004 FXT 5MT
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1,142 Posts
Discussion Starter #3
Thanks. So a 65mm would be a easier install then? Is the difference in diameter 5mm or a bit less?
 

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Premium Member
2007 Forester XT 4EAT-VTD
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2,138 Posts
I went with an AEM instead of the APS. Since it uses a rubber elbow to connect the pipe in the engine bay to the pipe in the fender, that entire issue is eliminated. Also, it connects direct to the turbo inlet so no afterMAF hose is needed. Overall, a nice CAI that I am very pleased with.

I used model 21-477C and it fit perfectly.
 

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2004 FXT 5MT
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1,142 Posts
Discussion Starter #5
That's another option too.

On my e-tune setup with surgeline I only listed stock airbox. But after reading that the APS intake does not require a tune, I figure I might as well get one since it wouldn't make a difference for the them right?

Would the AEM be the same thing? Either one should give a good 10 whp increase for a VF series turbo with a tune right?
 

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Premium Member
2007 Forester XT 4EAT-VTD
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2,138 Posts
The AEM does not require a re-tune. FWIW, with a VF48 I went from a 100% stock intake and a STi TMIC to a Perrin TMIC, Samco turbo inlet and AEM CAI and picked up 20 WHP with a re-tune. The tuner speculated a good part of the 20 WHP gain came from the CAI. Both the CAI and bigger (lower pressure drop) TMIC also made a noticeable difference in pre-boost throttle response.
 

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2004 FXT 5MT
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1,142 Posts
Discussion Starter #7
Is it 20 whp across? How did it change the low end?

So would it be more work for a tuner to tune it compared to a stock airbox? Would they be able to tell that it's not a stock airbox anymore?
 

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2004 Subaru FXT MT
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1,841 Posts
Is it 20 whp across? How did it change the low end?

So would it be more work for a tuner to tune it compared to a stock airbox? Would they be able to tell that it's not a stock airbox anymore?
Assuming the MAF was properly cal'd with the stock box and the tune was conservative, you can swap in any 65mm CAI without a tune.

The power statement must be qualified. You won't see that sort of gain on a TD04. But you will see 10-20whp from the mid range up on TD05/VF39 and up. As the turbo gets bigger, the more the intake will help.
 

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2004 FXT 5MT
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1,142 Posts
Discussion Starter #9
Yup the plan is a VF turbo. So it doesn't matter to a tuner if I use the stock airbox or a APS/AEM intake then? i.e. it won't cause more trouble/time for them to tune the car?
 

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2004 Subaru FXT MT
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Yup the plan is a VF turbo. So it doesn't matter to a tuner if I use the stock airbox or a APS/AEM intake then? i.e. it won't cause more trouble/time for them to tune the car?
Are we talking before or post tune right now? If you're still in the process of getting tuned, tell them. The more the tuner knows, the better.

But if we are talking you've already been tuned, and you want to add a CAI, you should be fine.
 

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2004 FXT 5MT
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1,142 Posts
Discussion Starter #11
Before. I only have the base maps based on the list I gave them which has the stock intake. I haven't sent them back any logs yet.
 

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Premium Member
2007 Forester XT 4EAT-VTD
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2,138 Posts
Is it 20 whp across? How did it change the low end??
No, 20 WHP combined between the Perrin TMIC, Samco turbo inlet and the AEM CAI.

Most of the gain in the intake work will appear in the upper RPMs (see composite graph below, compare blue and red lines). Because the Perrin TMIC is HUGE compared to the STi TMIC, I lost a little spool time having to pressurize a larger inercooler on the second tune (red lines), but gained noticeably improved pre-boost throttle response. The addition of the Aquamist water/meth injection system for the third tune (green lines) got it all back and then some. :biggrin:

 
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