[TowerTalk] acceptable boom sag ?

[Bob K6UJ]

I am trying to eliminate truss wires if I can on a 4 EL 20M yagi I am building.Using DX Engineering's Yagi Mech software I show about 5.5 inches of sag 
on each end of the 30 foot boom.  I am using 2" OD .058"  wall tube sectionsfor the boom.  The 5.5 inches of sag is with the center two boom sections sleevedto .116"  wall thickness.  Without the sleeved center two sections the sag is about 
7.5 " on each end.  New to using this software and not sure what sag is acceptable either.What are your thoughts ?
BobK6UJ