Mishimoto PCV catch can and PCV valve
 

Hi all
My car will be boosted very soon and I'm planning on installing the Mishimoto PCV catch can. Would I need to change the PCV Valve? If so which PCV valve should I go? And would I need to get a check valve too?
Thanks!

It's a complete kit it should include a check valve already.

so the mishimoto kit already has a check valve?

I can't see any PCV valve included at the product page. However, there is already a PCV valve on the engine block. You can add a 12mm check valve on the intake manifold side (blocking the blow out from intake manifold). The second check valve is recommended for FI.

So i can just use that boomba 12mm check valve without needing to replace the stock PCV valve on the block? I will be boosted very soon.
Thanks for the help!

When you have the oil catch can, the check valve on the intake manifold side is better than replacing the PCV valve. Boosted air can potentially leak from (or at least expand into) the catch can. Check valve will stop the air flow before going into the catch can.

Okay, all makes sense now. Should i bother upgrading the PCV valve too or is that overkill?

It is not necessary to change the PCV valve anymore with the check valve added. I would make sure the check valve is working before installing. Blow from both sides, it should not leak air in the opposite side to the arrow marked on the check valve.