I'm not sure about the HKS BOV. I'm assuming you are talking about the Type-S. My brother personally has gone through two HKS Type-S BOV in one year on his Supra. They seem to have a lot of defects now. A friend of mine with a Turbo GSR had the same problem. That is why I decided to go with Blitz. I've had that for almost a year and it's still doing good. My brother and my friend switch to the HKS racing BOV. They seem to be doing fine. They sound really bad ass too, just like the japan racing videos. I think I might be switching to that as well but they are really $spendy$ though.
Hope this helps
Also, you guy know that the fins can be changed in the Type-S to change the sound of the BOV. Normally they have a wistle to it, you can change it to a simmple phhshhh like sound or a sound like a donky getting the kickked in the nuts.