I am just starting my Sig 1/4 Cub and am building 3 degrees of right thrust into the firewall. All my planes have 3 degrees, including my Sig 1/5 Scale Cub, and they fly great. I am going with a Zenoah 26 CC Gasser for power. Good luck with yours.
FYI: The 1/5th Cub also lacked right thrust in the plans and the manual. Wonder if the forces of torque fail to exist at Sig?
SunDevilPilot