Until you put on a large turbo, stock bypass vlave is best. If you do the intake silencer delete (the big milk-jug type thing in your fenderwell) you can hear the valve really well. Cheaper too.

 

If you really want an aftermarket bov you have two choices, actually three there are atmosphere, recirculating, and a combination that allows you to change between the two. It sounds to me as if you want a atmosphere. The actuall install on any of these is fairly easy with just 2-4 bolts/screws, and the adjustment of the tension of the bov via shims/screws/top twisting. If you want more info on the pros/cons mostly cons on a stock car. Check out these thread: BOV Q&A-1 BOV Q&A-2
And for referenceCAI Q&A-1

 

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wrx dont run well all atmoshere, thats why it came stock with a resirculating set up, plus all atmosphere wont give you good performance, your car will back fire theres a reason why subaru design the car that way, most people get BOV FOR SOUND which isnt the way to go, i would go with performance wize, but its all up to you its your car, i would suggest 50/50 which is atmosphere and resirculation, it wont be as loud.. i purchased a TURBOSMART BOV, works real well, do your research find out what works best for you car not what sounds cool... hope that helps.. i'll list some 50/50 bov, when adj. a bov should release at low rpm u will know if its spring tension to loose if it starts to back fire, then increase tension on it, shouldnt be to stiff either use your ear...

1) Turbosmart
2) GFB
3) Aps
4) Worx

 

go with gfb stealth bov i have this on my rex and it wasn't to loud and also was easy to adjust the volume!!!!

 

i have a blitz dd works and sound fine

 

+ 1

 

GFB bov is the one i have. me like! its adjustable, you can run it closed open and adjust the sound. the only negative is price i paid $270 for mine.

 

Buy a used one. If you don't like it, resell it for the same price. Don't waste good money on something you don't really need for now. There's reasons why lots of negative comments are being mentioned. Also remember that as soon as the dealer sees that horn, bye bye warranty. Not that the warranty is worth anything for a Subaru. Pay to play is the rule.

 

https://www.i-club.com/forums/engine-power-ej25t-sti-2006-wrx-90/blow-off-valves-tested-me-57327/


-GDO

 

Well warranty stuff really depends on the dealer. BOV's have been known to cause some issues in WRXs, especially when combined with CAI, so be careful, I personally wouldn't get one. The possible problems aren't worht the sound.