How does a BOV add power? could you please explain that.

I always(and many thousands of people also think)thought the purpose of a BOV was to release compressed air during closed throttle to prevent compressor surge.

Btw Synapse synchronic BOV's are cheap chinese junk,along with the rest of their line of products,it's just all hype.

If the OP wants a good quality BOV that flows alot of cfm and does it's job flawlessly,get either a Tial or Turbosmart products.

I like the JGS Tools ones because they aren't fluorescent purple and/or look like spare parts from a frickin spaceship or something.

http://jgsturbo.com/jgs500bov.html

For performance, it's best to keep the factory bypass valve that recirculates the air back into the intake rather than venting it out the BOV.

I only have a BOV because my factory valve was getting old and started to leak. That said... SSQV ftw... it makes many sounds depending on the psi. Less than 1psi, it sounds like someone blowing through a straw. 1-5psi, it sounds like opening a fresh 2L bottle of pop. 5-10psi and it starts to make that whistling sound that everyone is familiar with. At 16+psi, it sounds like a venting bus.

It's a tad loud in the MR2 because it's a car that doesn't have the sound absorbant material under the hood. It's got many open vents surrounding the motor and the BOV's right by your ear on the other side of the firewall. I've heard the SSQV in many different cars and they don't sound anywhere near as loud as the MR2 at the same PSI.

I still have that blow off valve!

Its a filter btw.

Geddy RS +1 I cant stand the HKS.

I have sold a few of the Greddy Type RZ and everyone has seemed to like them but definitely not that cheap. I think HKS is the one most people inquire about though which would make me say its probably the most popular. I think its all on a personal preference though for me I would rather have a recirculating BOV instead of a vented to atmosphere just so I dont here the "psssssh" all day plus it give some sleeper effect to the car. A BOV will in no way increase your horsepower; however it will increase throttle response and lower turbo lag as the turbine is not being slowed down by built up pressure, though a little stupid that Wikipedia write up is somewhat right, the built up pressure will slow your turbine down meaning your will need more time to spool up and build boost so you can actually make your power, so in reality its just allowing you to access that power faster and not blow your turbo up.

I love the Bosch style BOV that came with my Hahn Racecraft Kit.

It's got a good deep throaty woosh, and sounds better than the typical "pew pew!"

Tial or Turbosmart are in my opinion the best. When it comes down to it, if your making real power then you wont be hearing the bov but only the turbo and wastegate....:D