I tried this build, and I consider myself a decent player, but in Elite STFs, I can't get this build above 1.8K DPS. How the heck are you getting 5.5K? Even our escorts are only getting in the 4.4K DPS range.
Unfortunatly the simple answer to this is something is wrong (and it's not my figures). Knowing that; lets analyze what it could be.
What instance are you taking your DPS figures from? KA is the best as it has the least moving around, Cure is clearly the worst.
What are you using to measure DPS, I'm assuming a parser that reads the combatlog, but their is more than one.
Is your parser taking into account shield damage? Mine as default does not, you have to right click the combat entry and tick 'include damage to shields'.
Also need to look at your Escorts, depending on the Escort (Defiant-R is the highest in game), without abusing fake DPS from FaW/TS (they hit targets that regen life, so the DPS is not on the targets you need it to be on). they are about 2k below what is possible. A really well built Escort (tac captain ofc) will pull 6.5K in KA.
Are you looking at the DPS in KA as a whole encounter? Remember that their is quite a wait between Stage 2 and Stage 3 (Gates > Donatra), so you need a Parser than can split the engagements up and totally ignore the damage and DPS on the Donatra as literally 1/2 of that engagment is waiting for her to come out of cloak.
I can tell you this, I had a mate of mine hit 50 two days ago, he bought MK XI green gear from the AH, didn't have the SSFM or Assimilated Console. He had never done an SFT before, let alone an Elite one. The ship was bought about 30mins before and never taken it in to combat. He did 3029 DPS in Infected Elite (Including shield damage), he died 6 times.
I am more than happy to run some with you this evening (I am in my Intrepid build at the moment though), possibly give you some advice, possibly advise what my parser is reporting.