In this paper, we are interested in providing deterministic end-to-end guarantees to the Expedited Forwarding () class of the Differentiated Services (DiffServ) model. We focus on two Quality of Service (QoS) parameters: the end-to-end response time and the end-to-end jitter. As packets of any flow can experience variable network delays and sojourn times on each visited node, the inter-arrival times can be shorter than those on the source node and burst arrivals are possible. This flow distortion increases with the number of visited nodes. To cope with this distortion, traffic shaping has been introduced. We focus more particularly on two techniques of traffic shaping: jitter cancellation and token bucket. We then study the influence of traffic shaping on these two QoS parameters, independently of the scheduling policy for THEEF class. In this paper, we show how to compute the worst case end-to-end response time and jitter of any flow in the EF class with and without traffic shaping, assuming that the class has the highest priority and packets in this class are served FIFO. We then determine when each one of the three techniques (no traffic shaping, jitter cancellation and token bucket) is the most appropriate.