In a truck with the same gearing, the .12 have a faster top speed then the .18 because it can reach higher rpms. But the .18 would have alot more torque and acceleration.

In your MT, you would like the .18 better because it has the low end torque to pull the 4x4 and it has the hp to pull higher gearing so you can get the top speed you want.

So I guess what I'm trying to say is the .12 would be best and fastest in a 2wd stadium truck, but the .18 would be best in your truck. Thats what I'm running in my MT2 and I absolutely love it.