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$Cost to make reliable 400 whp 2017 STI?

109387 Views 53 Replies 14 Participants Last post by  XJman
I'm thinking about buying a new 2017 STI. I'd really like it to make more power but would not want to have to worry about something going wrong since the warranty will obviously be compromised. So if I wanted 400 wheel horsepower or more what's the best safest route and how much would it cost?

I know all the basic parts evolved when tuning these cars for more power. But I want reliable power. So aside from all the bolt-ons like downpipe, upgraded fuel pump, exhaust, injectors, blah blah blah etc etc.

For reliability would it be necessary for forged pistons and a closed deck block? Or would the pistons be good enough? And what would the typical cost be for 400hp? I know for 300hp to the wheels stage 2 it's about $2900..
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1) I think you maybe reading "anger" in-to Zax posts. There may be some frustration there but I don't read any anger.

2) Getting answers may seem like "pulling teeth" to you.. but that is most likely because you don't quite understand that your questions are not as simple as you seem to imagine them to be.

3) I would direct you to off be reading Defiant Autospeed's post on NASIOC: Public Service Announcement "I Want 400WHP!..."

Good luck. :)
If you want 400whp, here:

ID1000 Injectors
Walbro 255lph pump
GTX3572R rotated manifold turbo
Killer-B ELH + rotated EWG UP (does this exist yet?)
E85 flex-fuel kit
Tuning solution (obviously)
TGV deletes
Parallel fuel rail mod
IAG fuel damper kit
Snow performance Water/Meth injection (you'll need all the det-resistance you can get)
Catless DP
Speed-density conversion
Killer-B Oil pan, baffles, and pickup (you'll need the extra oil capacity for cooler oil temps)

That should make 400whp on most dynos. The motor may last 100,000 miles or 1,000 miles. At these BMEPs, the motor could go at any minute.

Sure, you could build the motor for another $8,000-10,000 and it MIGHT last another 50k miles, but built motors rarely last as long as stock OEM motors.

At the end of the day, you might have an Impreza that cost you $65,000 and resells for $25,000. Or you could have a $40,000 Camaro SS (with 400+whp mind you) that resells for $38,000.

Of course while this set up will net 400WHP on most dynos, one would be still be quite foolish to not also upgrade any number of other things that will not last long with a doubling of stock power.

So plan on spending a fricking crap ton more money to get so-called DD "reliability" and you will likely never be able to get any of that money back out of it should you need to in a private sale (trade in will not even be an option as no dealer would touch it with a 100 foot pole).

Good luck slaying the reliable 400whp daily driver Subaru windmill, Don. lol

You should consider a B8 Audi S4

Sent from my SAMSUNG-SM-G890A using Tapatalk
Larger displacement and 2 more cylinders than the STi do seem like it would make for a solid choice. Not only are the peak numbers from the factory higher than the STi but I would imagine the power band overall would compare more favorably. I don't know Audis well but I would imagine that starting with a larger engine would make it easier to make greater power, relatively reliably.

Plus it has a MUCH nicer interior. It is more comfortable and more practical for a family. It is a sweet car.
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