Thanks everyone
I'm still a bit confused about Ball Python size/weight.
Amelia just wrote that her 2 month old BP weighed about 160g (When I bought Monty, he was 5 months old, 52cm and 114g. -- OK he had tapeworms in the beginning which we treated.)
He is now 1 year-3months old, 72cm long and weighs 322g. About a month ago, we upgraded him to bigger rats (30-40g every 7-10 days), which he snaps up like never before!!
He's not nearly as "thick in the middle" as most BP pics I see. Is he underweight?

If so, how should I go about fattening him up? 2 rats per feeding or 1 rat fed more often -- like right after he defecates the previous meal?
Any thoughts would be much appreciated!