That's right. Simply clip the hook end of the spring off and leave the spring in place. It keeps the butterfly from vibrating around - possibly messing up your mix and causing premature wear. If the spring is left stock, the servo has to work against the spring pressure every time you open the throttle - drains the battery.

Yea, dump the "stop screw", too. Let the servo determine the low end position. If the servo stalls against the "stop screw", you'll either bend linkage or drain the battery - fast.

CAUTION - If you remove the butterfly, be absolutely sure you reinstall it in the same position/orientation as it was.