hm dont really understand what u mean :/. do u whant a straight split around youre model? if thats whats u whant u could do this in a coupple ways. 1:split edge ring tool 2:cutface tool and snap it with shift to get a straight line 3:split polygon tool and just split around the model without care where the cut lines are and then go to vertex mode and snap the vertex so they allign. hope it helps.