[JSH]

Originally Posted by KingLT1

I run metco breathers on my engines. That being said the MM wild catch can has a breather so it should do the same thing, but you might try adding the Metco breather on the Valve cover.

I had a rear main go out on a new 5.3 LS(mild build) that was less than 1k miles old. Replaced seal added Metco breather, no issues since.

If you don't want to try the Metco breather, One thing you will want to make sure is that your breather lines are all upgraded to -10 and routed correctly for the MM wild can to vent crank case pressure efficiently.

MM says:

you can hook the valley plate adapter or spare valve cover port(s) to one or both of the outer ports on the stock black box, since it appears the exit of it is still connected to the cold air intake

you can also unhook the lines at the valve cover and blow toward the can
this should be very easy to blow, and may find a restriction somewhere perhaps also double check the fittings in the valve covers for not necking down on the hose size

if the valve cover fittings are -10 port, we can go up to full flow -12 with our parts