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So Monday I'll be picking my WRB 2018 STi from the shop with a new IAG stage2 shortblock w/ the following mods.
Grimmspeed 3port EBCS
Grimmspeed stealthbox
Grimmspeed Catted Downpipe
Invidia q300 catback w/ Nameless muffler deletes
Perrin AOS
KillerB holy header
IAG EJ baffle/windage tray/pickup combo.
Cylinder head valve job
Subaru JDM 12mm oil pump
BC springs & retainers
ARP head studs
ACT Street clutch kit
Cobb flex fuel kit
Cobb fuel pressure regulator
Injectors dynamics 1050s
AEM fuel pump 340LPH
Base tuned for break in period.
One of my main questions is should I go ahead and call the shop Monday before I head up there and get them to install a Cylinder 4 cooling mod? Is it still necessary? And I know depending on my tune after break in on 93oct and e85 my whp/tq numbers could range dramatically but I'm sure you guys have seen this setup or something similar, could someone give me a range I'll be looking at? And lastly where do I go from there.. bigger turbo? I have no idea where to even begin or what to look for there. I'll just enjoy what I got for awhile but if I was to guess I would say maybe bigger intake manifold? I love how the AMS manifold looks.. so mean.. any help would be great!
 

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With the Killer B header, you may find the cyl 4 mod to be somewhat useless, as by adding an ELH you take the strain away from cyl 4 that an UEL header creates (like OEM).
Can't really comment well on HP numbers, but if you are stock turbo, on 93 don't expect to go much further past 300-340whp. I'm optimistic on the 340 end because it looks like you had some head work done, and I don't know what effect that may have.
We don't have e85 here so I'm clueless on that one, but high 3's?
Bigger turbo; if I was going that route, I'd be doing a Garret gt30 or gt35.
One is more power, one is faster spool but still big power.
I'll let those who know chime in on the turbo front, as I just admire the idea from afar :D
 

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With turbos you have to be careful what you wish for. Most tuners will bring spool in similar to OEM because it's much less strenuous on the rod bearings vs bringing it on light a light switch with a quick spooling setup.

If you do want to go bigger turbo, keep in mind you'll have to replace some of the things you've just bought, like fuel injectors. I would recommend driving the car for a while. Break-in, tune, and enjoy it for a while. Learn where you want power, how you want to use it, and how to stay within your builds safety limits. From there, you find the setup that matches your needs.
 

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2020 Subaru WRX STI
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I make about 340-350whp on e85 with stock motor and turbo. I would advise that you just get situated with the car first. Flex fuel and all those mods already changes the feel of the car dramatically. Take your time with modifying it. Take time to enjoy your changes before tacking on more. Consider what your use for the car is before adding more. Because not everybody wants a big turbo like 6+ because its not usable on the streets since the spool time is high in the range.
 

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Cylinder 4 cooling even with a ELH? Is there data backing up that Cylinder 4cooling works? I would think subaru would sale that part by now
There's data backing up that it cools the cylinder. I would think they would also include ELH on the new STi's since it's "proven" to help, but they don't.
 

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There are some good threads to search for on here about this, some going over data. It is an interesting point considering the low cost of this compared to all the engines that have been warrantied, why the change never happened from the factory. Could come into play at power levels beyond warranty coverage though. The one thing I鈥檇 look for but haven鈥檛 come across any detailed data on is the impact to the cooling for the other side of the engine and turbo. Without really knowing that, if it were me I鈥檇 call it good with those sweet headers you just put on.
 

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Cylinder 4 cooling is one of the best things you can do for evening out cylinder temps. I'd place it higher than ELH, from strictly a safety perspective.
 

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Cylinder 4 cooling is one of the best things you can do for evening out cylinder temps. I'd place it higher than ELH, from strictly a safety perspective.
^ We do both on any car that comes into the shop, along with a few other things. Why not do everything you can to promote longevity, right? I'll take that over paying for an unexpected engine build any day!
 

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I didnt realize there was that many cyl 4 cooling brands... which would be the best or are they all the same? i noticed one is all rubber hose I believe ....... brands: tq solutions, DOMtune and etc.... which would be your choice and why?
 

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I'm all for supporting original developers. But, the one mentioned above all to often treats his customers poorly. This is very clear in his online presence. I will never support him.
 
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