We sell two different rear seats. One will need the factory roof supports and one will not need them.
The rear seat with the Aluminum Diamond Plate flip deck and safety grab bar does not need them, and is not included with the kit. The factory roof supports and basket behind the front seat stay in place. You will remove the golf bag holder only and the rear seat will bolt on to the back of the golf cart from there. This kit does come with everything needed to complete installation.
The other rear seat we sell is by GTW and has a Black Plastic Embossed flip deck and does not come with a safety grab bar. This seat kit you would discard your factory roof supports and use the new ones provided in the kit.