When do you need to upgrade and how well will the stock one hold up?

 

bump

 

We've had the stock one hold around 19-20psi, but it can vary slightly from car to car. Generally speaking anytime you want to hold more than stock boost, I'd recommend a new BOV.

The MR works great, and is inexpensive.

 

How much psi can the MR bov hold compared to a HKS?

 

The MR isn't a BOV, its another diverter valve just like the stock one. I would recommend the APS BOV.