the motors (i4 and i5) are simply the i6 from the new trailblazer, which is a very technically advanced motor with dohc and what not, with cylinders cut off.
just like the 4.3 was just a 350 with 2 cylinders cut off.
the motors are monsters compared to what's out right now.
a family member of mine works in the plant that builds the motors, and they tested an s10 with the current 4.3 and one with the i4 and the i5, both of which wooped it's ass.
also... i know the body is ugly, but keep in mind that the frame and suspension setup on the s10 is from 1982, when that setup first came out. all they've done is change the body on it... i think that truck is completely all new...