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Discussion Starter · #1 ·
Never owned an sti before, or even a subaru, I was wondering if they came stock with a blow off valve and if they do, what do they sound like? A friend of mine has a turbo on his car and he blocked off his blow off valve to get that stutututu sound that everybody is in love with (or at least I am). Is it just a whoosh and would I have any problems if I did modify the valve? From looking around the internet I shouldn't have any problems especially with stock boost levels and it shouldn't damage my turbo if the flutter only happens when I let off the throttle. Any insight is appreciated.
 

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Discussion Starter · #3 · (Edited)
He blocked his BPV so the turbo can experience compressor surge? Surge isn't particularly nice on the turbo... If you want the sound, put in a BPV and add an intake (and tune) and you'll get plenty of sound without potentially shortening the life of the turbo.
Yeah that's what he did with it, he put a piece of metal in the way of the BPV, that year of STI doesn't come stock with a BPV?

I saw some threads saying a short ram intake would be the way to go, do I really need a tune if I put in a new intake though?
 

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Audio system is for sound
Engine makes the car go.
OK sound is a priority for you engine?
Want to see what you do with the audio system to help it go . . .

Yeah I know there is always a lot of talk about exhaust sound - and I don't like mine too annoying . . .

Oh, All (stock) STIs have BPVs - and they work!!!
Yes you need to tune when you mess with how the engine works.
 
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Discussion Starter · #5 ·
Audio system is for sound
Engine makes the car go.
OK sound is a priority for you engine?
Want to see what you do with the audio system to help it go . . .

Yeah I know there is always a lot of talk about exhaust sound - and I don't like mine too annoying . . .

Oh, All (stock) STIs have BPVs - and they work!!!
Yes you need to tune when you mess with how the engine works.
I don't really care about the go, I just want my turbo to sound cool lmao

no need to be a condescending asshole about it.
 

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I don't really care about the go, I just want my turbo to sound cool lmao

no need to be a condescending asshole about it.
It might sound like he is being condescending and maybe it could use a bit more tact sure but ultimately I believe he is trying to guide your train of thought onto things that are more important.

I've owned 3, 05 STis and the very first thing any Subaru owner will tell you is that blow-off valves on our cars without a tune ends up in performance issues or worst if you go with a shitty BOV that ultimately adds nothing to your build and the potential for it to go wrong is very high. For example, you're buying a used 04 which is mostly stock except the "exhaust"? What kind of exhaust is it? Is it aftermarket? Is it bigger than stock? Are you sure they didn't do a full TBE on it? Did they tune it for it if they did?

I find that very rarely does an STi owner "just" upgrade the "exhaust" without doing other things. If it's truly just the exhaust, then it might not even need a tune but your money out the gate might be better spent on taking it to a local tuner to check it out for you first. A good rule of thumb I learned is that if anything changes the flow of oxygen going in and out your car, you need a tune. Adding pieces like that without a tune is asking for underperforming jittery car.

Most Subaru owners tend to skip on the superficial engine mods that don't add to the performance of the car. I'm not saying they don't mod it, but practicality and whether or not it actually does anything usually take priority, then the bling comes. I like to put my bling on things like battery ties and other stuff. I mean, whats the point of adding a cool "whoosh" sound when you're getting your ass handed to you by a Dodge Neon because you chose noise over performance?

Long story short, you could put a BOV on your car but it won't be as easy as hacking it in. I mean you could, but you will more than likely end up wrecking your turbo which would set you back a couple of grand.

Besides, BOV without the performance to back it up is Honda driver bullshit :D We Subaru owners are all about that boxer "rumble.

Here is some good info on BOV: Blow Off Valve FAQ: Read if you are thinking of buying one! - NASIOC
 

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This site used to have amazing performance information. It still has a higher signal to noise ratio than many others - which with so little STI change and other platforms catching up has meant less activity here. I am sure the site owners would just as soon have the traffic and loose the signal to noise ratio. When the signal to noise ratio decreases to much for me, I won't be here very much and certainly not as a premium member. I can use Facebook to see what kind of noises people cause their cars to emit, often with no knowledge whatsoever of what it means for the car or its performance.

I admit I am a bit of a jerk about it. - but in the end I did answer some unaddressed questions for the OP.

Regardless, stock STIs all have BPVs specifically to prevent the damage that can be caused when compressor pressure is "inverted".

Audio-wis I was half serious! Someone should market noises people can play while they are driving. Could be controlled by a G sensor to play the "right" noise - say BOV, wastegate, and trans whine when they let off the pedal and decelerate detecting the downshifts.

ADDED: Yeah. add all the above and some simulated rattles and bumps and you could have a car that sounds just like my 15 year old, 260K+ Mi Built Beater :) :) :)
Yeah, that and some solenoids to kick you in the seat every time you see a bump :) :) :)
 

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Boy my old admin fingers want to touch this thread.
 

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Did I break any site rules? If so I will be more careful not to in the future :)

A warning before being recessed would be in order :)
 

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I don't really care about the go, I just want my turbo to sound cool lmao

no need to be a condescending asshole about it.
Let me be a condescending asshole! The sound you want may kill your turbo. You have weird priorities. Fall in love with the wastegate sound. You will soon get tired of it...
 

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Did I break any site rules? If so I will be more careful not to in the future :)

A warning before being recessed would be in order :)
You're fine. The issue is we've been answering versions of this question for 15+ years now and it gets quite old.

To the OP, no one is truly being a jerk here but you have to understand where they are coming from. If you want to buy a car so it can make sweet shifting noises, go for it. Put the loudest and most inefficient BOV you want on it and enjoy the car until it dies and you have to go rebuild or dump it and buy a new one. BOV's without supporting mods and/or tune will harm your engine, period.

All of these subaru's came with a BPV (bypass valve) which acts like a BOV but recirculates some of the air back into the intake. BOV's are typically full atmosphere air dumps where none gets recirculated but the problem is the computer isn't compensating for that loss of air coming back into the intake and will cause the car to run rich inbetween shifts and can cause harm over time.

This answer, and many like it, are flooded around this forum. There is plenty of good info, search and enjoy. If you get the 04, love every minute of it but don't expect it to last long if you don't take proper care of it.
 
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