If you're just driving KL roads only and having the occassional sprint on the highway, it's not going to be absolutely necessary. However if you thrash the car up and down Genting weekly and cook your ATF frequently (you can tell it's cooked when the gears refuse to change) then it'll be in your best interest to have a gearbox cooler. Lengthen the lifespan of your ATF and gearbox. But if you just have a lot of money and just want to modify something, having a ATF cooler won't hurt.