Brake system update

I would like to improve the braking system. Drive now ate discs and coverings. 300mm ventilated in front and 300mm unventilated in the back. There are 300 316 and 336 mm discs in front, after I drive in winter 16 inches no update is possible? How is the conversion at the back ventilated? Has anyone done this yet? Is this noticeable? Thank you!