well I apologize before hand if I'm talking outta my ass, I havent researched the changes to the '08 at all. However torque, especially on small displacement motors is a product of port velocity. The '06 design benefitted by smaller ports and valves, because in doing so they amplified the engines vacuum by decreasing the port size. Vacuum doesnt change but reducing the amount of room the vacuum has to operate within, increases the "suction" of the motor, moving more air at virtually all engine speeds. This method was adopted on the '06 because the increased port velocity increased power on the motor enough to outweigh the flow numbers for the '05 with its larger volume head design.
My assumption (again sorry I havent researched) is that the '08 has larger ports, valves, or lift similar to the '05 motor, but as the similar torque figures show, they were able to maintain a similar flow on the low end to the '06 while making the '08 larger lift design do what it does natively, flow big numbers up top. The slightly higher peak tq for the '08 indicates this as well. As our '06 ports start to gasp for more the '08 opens up and finds another gear.
