M13A is the one you get in a Liana.
Its like G13B, an all Aluminum DOHC block.
I have some reservations about a G16B in a Cultus, If you dont have a Stock Power Steering running yours get iT done too.... The torque in that thing makes iT hard to Control. Get a new Suspension Setup, that thing is HEAVY..!
G13B/M13A are Lighter... and might blend with the Stock suspension setup altought getting stronger parts is RECOMMENDED.
Waisae, I still will suggest you to, if possible go for an M13A Conversion and that too by authorized personnel. It would ensure everyday driveability + untapped fun when you desire it.