What is the largest domestic cat breed?

(I was wondering what breed of cats are the largest!)

Answer:
Ragdoll: Altered males will top the scale at 15-20 pounds; females usually weigh between 10-15 pounds.
Maine Coon: The males average around 12 to 15 pounds, with a few going 20 pounds or more. The females are smaller, averaging 9 to 12 pounds.
Persian/Himalayan/Exotic: Males and females are usually 10-15 lbs due to bone density. They are smaller in size then the Ragdoll or Maine Coon
The Norwegian Forest Cat can be very large (20lbs+) but since it is a natural breed the size varies line to line.
These are all long haired breeds as well (except Exotic, they're a medium hair breed) so they look even bigger.
A new breed called The Savannah is being develped by crossing an African Serval cat to a domestic cat. The people developing the breed are aiming for 20 pounds average.