I'm trying to make a list running Whisper and Vessery but I'm not sure how to complete the list... So far I have;

Whisper: VI, FCS, Agent Kallus, ACD (41)

Colonel Vessery: VI, Tractor Beam, TIE/D, Twin Ion Engine Mk. II (38)

This leaves me with 21 points left to use. I thought about taking Mauler Mithel with predator and Twin Ion Engine but I'm open to any suggestions or tips that anyone might be able to give me.

You'll want an initiative bid running Whisper, so you probably only really want to spend 19-20 points. I like the idea of Mauler, since you can bounce people into range 1 of him with the Tractor. Maybe him with just Predator would be okay, or maybe something like Snap Shot if you want to go for a bigger bid?

Not Mauler. Take something with the Target Lock action to assist Vessery. A Sienar Test Pilot with title and Autothrusters is 19 points. That also gives you the initiative bid for Whisper.

I like the Sinear idea (but that's a great ship anyway). Alternatively Episilon Leader, still can have TL, but being able to do reds (ie K-turning Whisper :-) ) then remove stress and carry on could really mess with opponent.

As an alternate drop Ion (or VI for adaptability) and get Pure Sabbac for a load of red dice per turn :-)

If of interest my preferred build with Whisper and Vessery would be:

Vessery: Swarm Leader, Title

Whisper: VI, FCS, ACD, Intel Agent

2 x Academy

Relies on Whisper FCS to get locks for Vessery, but its a lot of red dice + blocking ability.

Take Sienar, you will want to block jumpmasters so they cant b-roll and block you, and since you are taking init, you can block K-bombers as well. I flew an Epsilon with my Vess/Whisper and the blocking is soooooo important. Blocking that white sloop on Dengar is the difference between winning and losing.

Countdown and get rid ok MkII on Vess for a 2 point bid.