mine is 12.5lbs and I have exact shock setup as you do. 4 1/8 buggy shocks and 4 traxxas big bores. try to put these springs on your 4 traxxas shocks, will help with car hitting the ground on big jumps.
http://www3.towerhobbies.com/cgi-bin...?&I=LXCSE0&P=7