Keep the stock IX metal recirculating valve, it'll hold 25 psi without any of the driveability issues that comes with most aftermarket ones. It can also be crushed to hold aproximately 29 psi if you're in need for more boost. I'm an example of many that re-upgraded to the metal valve because of the on/off throtle problems that the other 3 BOV(I don't wanna name brands) that I tried was having at the track.

 

I've changed my stock aribox to an AEM intake.. (not for the sound..lol.. )
but hell, the pssssh sound is so much louder...

 

Actually the stock evo 9 valve's hold 27 psi more then that you need to crush it,did to mine work's great no issue's.