I would have 2 dbb, beam array and a torp up front with 2 turrets, beam array and torp in back. The excelsior has the turning radius to keep your targets in front of you in PVE. use BO3 with either a HY2 or TS2 for maximum forward dps with DEM. You should see a noticeable increase on your forward targets.
Note: I would NOT take this build into PVP. Use 6 beam arrays, 3 fore and aft, and broadside the heck out of people.