That's not a simple question.
Any time you place more demand on the motor you require more amperage, good batteries and good cables.
A lot depends on what you are doing with the cart, many have rewound motors and done nothing else with good results.
The recommendation is if the cart is lifted with larger tires an upgrade to 4ga cables and a 400 amp controller works best. If you regularly carry passengers with a rear seat, the above upgrade is recommended. If you have both large tires and carry passengers, the upgrade is necessary.
The F-N-R switch should be fine.