If it's got one of G&G's wonderful mosfets in it, yes you have to use an 11.1v otherwise you'll have no end of problems. I've found that G&G's old mag issues have been resolved with this new iteration of combat machines.
An Army armaments R36 from TG, replacement bucking, recoil spring and LFS disc pack to lower the fps to field-able levels from Milspec. Excited to see what the gun is like.