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Old 05-10-2004, 09:25 AM   #1
Scooby Specialist
Member#: 27915
Join Date: Oct 2002
Chapter/Region: Tri-State
Location: Southern New Jersey
2004 Subaru WRX STi

Default 3/16

does the 3/16 mod inslude the sti? i was ordering a worx dual stage blowff valve and saw it on boostkits.com. it seemed interesting and i was curious if that included the sti with the wrx
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Old 05-10-2004, 05:54 PM   #2
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Chapter/Region: Tri-State
Location: brokenmotorsports.com
Team Broken: V6 GF


lets be a little more clear with the subject lines please.


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Old 05-11-2004, 10:58 AM   #3
E. Nick
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Chapter/Region: BAIC
Location: Atherton, CA
Mac MP4, Vip ACR,
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The ECU learns around the 3/16's mod very quickly. I believe God also posted some potential hazards of using this mod a while back.
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Old 05-11-2004, 02:06 PM   #4
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Chapter/Region: NWIC
Location: Austin, Texas, USA
The 93 W/EJ20K
Series 10 FRS


yes the 3/16 mod is a BAD IDEA for the sti aswell

don't do it
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Old 05-11-2004, 05:03 PM   #5
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Join Date: Apr 2002
Location: SE WI
2005 Leg.GT L wagon

Default 3/16 mod detrimental on WRX???

Two years ago I took out the restrictor in the little wastegate hose and replaced it with a 3/16" straight coupler.

I don't get over 14.5 lbs boost in any gear and everything seems fine.

For about 6 months I used a TEE 3/16" with one leg open to atmosphere. In 3rd, 4th and 5th it would spike at 17 psi and then drop back immediately to 14.5 psi.

The inference I get from the preceeding entries indicates there could be a problem with this mod. Could you please clarify? I haven't followed the original "mod" thread in years.
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Old 05-12-2004, 10:09 AM   #6
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2004 STi w/o wing
Aspen White / Silver


Not that I'm anything close to an expert, but a few days ago I did several searches on this mod. I'll give a quick summary, but as usual, read up and draw your own conclusions.

The general consensus is that the 3/16 mod does nothing to improve performance, and in several cases, causes the car to behave oddly.

Many people reported absolutely no difference in performance when they went back to stock condition after months of driving around on the 3/16 mod, and in fact were happy that their cars started behaving more "normally".

I have a strong suspicion the 3/16 mod is a holdover from a number of folks who previously owned DSM's and removed a factory restriction from the boost control solenoid. That mod *did* seem to improve performance without making any difference in the day-to-day behavior or reliability of the engine. It opened up the piping to about 3/16's also.

I guess several people thought it would work well on scoobies but that doesn't appear to be the case.

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Old 05-13-2004, 09:01 PM   #7
Hiz Dudeness
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Member#: 60319
Join Date: Apr 2004
2004 STI
Java Black


This is my fourth turbocharged car. Every single one before got more boost by making the restictor smaller, not bigger. The air flowing thru this restictor is to the wastegate actuator. By allowing more air to flow to the actuatoor you are actually hurting your boost response. This is why some say that the torque curve feels smoother. Just use some sense, the mod straight up sucks. That is why no one has dyno proof of it being a good mod. Every boost controller made(manual or electric) delays the amount or timing of pressure or pressure sensed by the wastegate actuator. Electric boost controllers generally work better than manual beause they can use a stepping motor and solenoid to allow faster boost response, better peak hold and are overall more user friendly. Flame if you want or if you think I am wrong, but I work for suburau currently and I have owned a tt rx7, still own a tt z and yes at one time a turbo honda. So I feel I have my credentials in order. Koods to soa for bringing us such great cars. For 2005 every model subaru offers in the has a turbo version. Now how is that for understanding customers desires?
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