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04 FXT
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40 Posts
Discussion Starter · #1 ·
I was checking out cobb's access port site and noticed the tune with a vf39 and sti TMIC is onlt 5 hp more than the stage 2 tune. If that is correct it seems like a lot of $$ and time for a very small gain.

So...are those number true? have you guys gone from a stage 2 set-up to the 39&tmic setup and noticed a big difference?

thanks for the input
 

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The Sub kit guy
2005 Forester X & XT VF39
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13,008 Posts
You can ingore those numbers. Peak numbers don't explain how different they drive. A VF39 is a BIG step up from stage two. It holds boosts much better than the TD04.
 

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2004 fxt A/T
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2,567 Posts
It is about usable power AKA area under the curve. The VFXX has much more area under the curve and take a step in the right direction of matching our close gear ratios. For the record Cobb OTS maps aren't that great, AFAIK they simply raise the PSI and make no other changes what so ever. They are far from optimal, you leave a LOT on the table. If you don't already have a AP look into opensource. Look through the member's journals, there are plenty of people that run VFXX's on this forum.
 

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Premium Member
2017 VW Golf SportWagen 5MT
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10,784 Posts
Worth it vs. what, a stock TD04? For a street car? Absolutely. TD04 is a horrible turbo for our car and OTS Stage 2 map makes it even less drivable IMO. The power band is alot more usable with a VF* and you can get better gas mileage to boot. 5th gear on the freeway is like your 3rd now.

Do not pay attention to any numbers you see anywhere. Find someone with a modded car, go for a ride, talk to them.. Ignore everything else (which could include forum info as well, I suppose). Forget running OTS maps unless a good tuner okays it.

Stan
 

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Registered
2004 Subaru FXT MT
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1,841 Posts
Comparing apples to apples, a VF39/43/48 is worth 50-60hp more than a TD04...not 5hp. Perhaps a stock VF compared to a full stage 2 td04 is only 5hp.
 

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Premium Member
2017 VW Golf SportWagen 5MT
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10,784 Posts
^^ +1, I'm at 256whp/256wtq with VF43 vs. 188whp/211wtq when stock, measured on the same dyno. My tune is extremely conservative at 14psi target. In reality, the drivebility is night and day -- it's a different car. Off the line it pulled harder than my friend's stock '07 STi.

I ran it at Stage 2 for a while and it was alright, but I kept hitting boost cut and throwing CELs. There was a bit more power, but stock the car ran smoother and was more consistent when pushed.

Stan
 

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2007 Forester XT
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311 Posts
God I love you guys! LOL
Good info to the guys (like me) who haven't been down that road yet. Let the elders find out for us!

Now let's hear some TD05-18G info! Seems my eyes keep going that way

Sorry meathooker-didn't mean to crash the party...
 

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Administrator
2004 Forester XT Premium 4EAT
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29,431 Posts
Yup... went from 186 whp and 210 wtq on the TD04 to 247 whp and 312 wtq with the VF39. Oh, and that's with a 4EAT. Completely transformed the car.
 

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2004 Subaru FXT MT
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1,841 Posts
God I love you guys! LOL
Good info to the guys (like me) who haven't been down that road yet. Let the elders find out for us!

Now let's hear some TD05-18G info! Seems my eyes keep going that way

Sorry meathooker-didn't mean to crash the party...
A VF39/43/48 is a great street turbo for the 2.5L, but, its still a bit small. An even better match is the 18G TD05 8cm that you want info on. Personally, due to higher cost to get a 18G, if you don't go 8cm, stick with the VF.

An even better match would be a GT3071R or a BW S200, but now I'm starting to talk serious money...

For $300-400, its hard to beat a VF...
 

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2004 2.5xt
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122 Posts
Just my 2 cents, I like bypassing these "stages" which don't exist in the DSM realm I came from. I do this because Its better to get a pro-tune no matter what because even with the same parts your car will act differently than the guy next to you, so I just go with whatever parts are going to get me to where I want to be and have it tuned. I went straight for a VF41 with some other small mods to give my forester some more pep and damn, did that do the trick. ~305whp* and ~320wtq*, I still find myself giggling due to the night and day difference from what the car used to be. I use this for a daily drive and I track it every now and then at PIR with some coworkers that have STI's, EVO's, RX8's and a Lotus Elise and I can pass just about all of them coming out of corners and on straight aways (no suspension yet).

In short, I'd skip the whole stage 2 thing and just go straight to the VF** turbo and STI TMIC setup.

*I noted these numbers as they are from the Dyno, not all dyno's are the same.
 

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2004 Forester XT 4eat
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545 Posts
if youre looking at a vf39, you might be better off holding out for the vf43. the upgraded wastegate design is a lot better and you dont have to worry about any cracking. im waiting for this kid from my town to start his build so i can snatch up his turbo for cheap.. seeing as im the one who tells him what to do to his car it shouldnt be too long.. :lol:
 

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Premium Member
2017 VW Golf SportWagen 5MT
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10,784 Posts
Time will tell if the VF43s don't crack as much as the VF39s do. Truth is, even with huge cracks VF39s hold boost well and run for a very long time, just talk to tuners.

Stan
 

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2004 fxt A/T
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2,567 Posts
if youre looking at a vf39, you might be better off holding out for the vf43. the upgraded wastegate design is a lot better and you dont have to worry about any cracking.
I'm looking at a low mileage vf43 (less than 20k) right now that has a crack, is it as big as the vf39's no but there non the less. Not concerned at all about it and 100% happy with the turbo as a whole, it is pristine with ZERO shaft play and never seen a drop of oil on the hot side.
 

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Premium Member
2008 FSXT 4EAT
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4,143 Posts
Is anyone running an EWG with their VF39/43/48 4EAT? I'm thinking about an EWG, since my FSXT is no longer my daily driver I won't mind the sound...actually, I really like the sound. :icon_wink:
 

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2005 Sequoia, V70R auto
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2,869 Posts
OP, you're the one that's in boise right? If you want to compare apples to apples, take a ride in mine and you'll feel the difference. I know you've ridden in it before, but you'll be able to directly complare a stg II against a tuned vf34.
 

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2004 04 FXT MT
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8 Posts
Sorry to bring up a old thread, this is my first post. But anyways I am in the process of buying a 04 FXT with 190,000 miles and a bad turbo. I plan on pulling the motor and doing doing head gasket, water pump, timing belt, etc. Basically I want to know if it is a good idea to upgrade to a V39 since I have a high mileage engine. or play it safe with the td04L? thanks guys, like the forum alot so far.
 

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04 forester xt
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969 Posts
do the vf. my vf43 is still sitting in the box waiting to get installed. i just have to decide on which intercooler to go with. ive been thinking about the fastmotorsports tmic from import image racing or turboxs which is alot more money
 

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Premium Member
2017 VW Golf SportWagen 5MT
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10,784 Posts
Yes, do yourself a favor and get a good-condition VF* turbo. You will want the supporting modifications as well -- TMIC, larger downpipe, STi bypass valve, a catless uppipe (this is pretty much a must -- later OEM uppipes are all catless because the catted ones like you have kill the turbo as the cat disintegrates with age) and a good tune. Good, safe tune is a must. Otherwise, just stick with a TD04 from another FXT, and a catless uppipe.

Welcome, BTW.

Stan
 

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Registered
2005 Forester XT 4eat
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4,581 Posts
Sorry to bring up a old thread, this is my first post. But anyways I am in the process of buying a 04 FXT with 190,000 miles and a bad turbo. I plan on pulling the motor and doing doing head gasket, water pump, timing belt, etc. Basically I want to know if it is a good idea to upgrade to a V39 since I have a high mileage engine. or play it safe with the td04L? thanks guys, like the forum alot so far.
Before putting a bigger turbo on, make sure you have no other mechanical issues, e.g. oil consumption, smoking, misfires, and get a leakdown test to make sure the cylinders are in good condition. If everything checks out, mod away!
 

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04 FXT, 61 Stude
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1,735 Posts
The weird thing is.... my forester felt faster with the td04 due to the initial hit the turbo has when it hits boosts, but since I installed the vf39 (and with a great opensource tune) I'm amazed that I can hit "the legal speed limit" without even knowing it. It drastically improves the drive-ability of the car AND makes it an absolute beast. I love it.
 
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