Do I need to install belts or complete kits?
You will be aware that both the timing or synchronous belt drive system (SBDS) and the auxiliary or accessory belt drive system (ABDS) play a key role in the performance of the engine. They require careful inspection and regular replacement of components. Gates guidelines for replacing serpentine belts, timing belts and elastic belts can be found here.
Remember that the best way to guarantee a reliable belt drive system is to change the belts and all related drive components at the same time.