Bonded DSL and 50E

So I upgraded from 40/5 DSL to 140/20 using bonded DSL.  If I hook my laptop straight to the Modem I can get the speed.  Once I turn on transparent mode and hook it up to a New Fortigate without any security policies I can only get 1/2 of the speed... 70mb... Any thoughts as to why or anyone else have this issue  Zyxel 3000z modem and Centurylink