I have had nothing but excellent results with POR15 as well.
Just make sure that all the pain is removed, and any dirt or rust dust etc. The product really likes to be in contact with bare metal.
I brushed on 3 coats on my beetle pan almost 7 years ago, and it still looks new (if fact it looks sprayed on). No chips, nothing.
I did not use metal ready but I wipe the surfaces with gun wash.
Another example is the bottom of my gastank. This stuff is bullet roof.
No I don't work for POR15...
but you will not be disapointed.