How much boost can these hold?
Stock 03 Evo BOV
JDM MR BOV

Id prefer to stick with these, then to buy the aftermarket.
Im thinking of running mid to high 20s.
Forge RS would be my choice if those two cant hold the boost.

Also i have the BR manual boost controller, how many turn is equal to 1 or .5 psi?

Thanks.

 

Stock begins leaking in the teens, but it can hold the stock boost fairly well.

JDM MR DV can go up to 24-25psi max before becoming a hindrance.

If you plan to run 25+psi daily, then you should get the Forge RS.

You can't ask what a single turn on an MBC corresponds to. You just have to go out and test it on your car to see, because it's not an exact science or measurement. All cars are different.