Skidplate question

I am expecting an MSR skidplate to arrive soon.
Their website mentioned a simple foam packing that fits the gap between the bike and plate, to keep out mud and crap...and maybe noise issues.
Is this a good idea?...any thoughts?

metal skid plate against metal frame = vibration noise at certain rpm's

def put something, I used one side of velco (fuzzy side) and stuck it to the bottom of the frame.