Hey, I'm just kindof wondering why there's a need for right-sidethrust in regard to where the engine is mounted. Thanks!

The torque of your engine turning the prop clockwise (from the rear) exerts force on the rest of the plane counter-clockwise (equal and opposite reaction). This force tries to make the left wing drop down, which in turn makes the plane want to turn left. This is further affected by "P-factor" of the propeller, which has to do with the angle of attack of each blade of the propeller. It puts additional force in the same direction.

The right thrust is built in to compensate for that force, and it makes your plane fly straight instead of always wanting to turn left.