I have 4 v-Spec engine's. 2 are RBMod, 1 is JPMod and 1 Stock. 1 of the RBmods is actually a VZB with a mod V-spec piston and sleeve. All my engine's were upgraded to TKO ceramic bearing's. They all are fast. The JP has more top end and is smoother than the rb's. The rb v-spec is a rocket on the bottom end. The mod VZB is pretty good all the way around. I would say that the V-spec is fast stock. The mods make them perform better. It's like buying hopups for your buggy. Is it worth it. Hell yea!