The 1st gen 4G63 motors in the Eclipse models have many more advantages than the 2nd gen. People actually swap out 2nd gen motors with 1st gen motors because of this fact. Some examples include a bigger throttle body and intake manifold. You can't even compare a GS to a GST, they are completely different motors. The GS isn't even turbocharged. So your friend is actually making quite an improvement in performance even though he is buying an older car.