Are you sure its flat? someone has them and can confirm these? I saw in few forum said it helicals...
The spring will be Guarder sp120/130.
About my FPS, be cool

I leave very far from you (Europe)
So now, the qustion is what set to pick up?
Here is something interesting I found:
PROMETHEUS
High Speed 16.45
Standard Torque 18.72
Double Torque 23.78
Triple Torque 25.84
Max Torque 36.81
SYSTEMA
Ultra High Cycle 15.50
High Speed 16.45
Standard 18.72
Torque-Up 23.78
Super Torque-Up 27.50
Ultra Torque-Up 36.82
Infinite Torque-Up 45.00
According to these, what set shuld I pick up ?
My set up is G&P M160, Guarder SP120/130 and 11.1V lipo.