PCV hose diameter?

[bcfromfl]

I've tried to use the search extensively, and haven't found an answer. I'm upgrading to TopZ's A2A system soon, and am going to add a dual catch can system with breathers. I found a good-looking catch can from Damond Motorsports, and they have two models: one with 3/8" barbs, and the other with 5/8".

The only somewhat helpful info shows PCV hose sizes for our car in mm, but I'm still unclear. Also, the FSM is no longer online (at least where I can find it). Which would be the best match...3/8" or 5/8"?

My speed shop recommended using MickeyMouse catch cans, but I can't get them to respond to their web form for questions. Anyone have an alternative phone number for them?

Thanks!