496HO you get 1 factory.
2 if from a certified installer.
Can purchase up to 5 additional on top of 1 year factory or 4 additional on top of 2 certified installer warranty. (Total of 6 years maximum).
I know of no extended warranty program for 525EFI.
Passport used to offer extended 5 years on the 500EFI, but now Passport is owned by Brunswick, who owns Mercury, which may/may not still be applicable.