Its a lot more expensive than forge splitter valve but I've been eyeing this one.
It's much larger than the forge splitter and I think it can support much more horsepower.
These are rated for up to 600 HP(medium turbo). They are made for evos and subarus.
They do come with different springs but you can change the opening speed with just a turn of the anodized top. The slower the spring and setting, the more boost is forced back into the intake before it's vented to atmosphere.
It's pretty cool. Also it comes with a block off piece that screws on so you can turn it into a full DV or full BOV It flows really well.
It's quite a large valve.