@Mad_Irishman
IIRC, I built the Nemesis to be just enough to reach 6 slots, I've tried bumping the nemesis up to 7 slots, but I can't find a way that wouldn't jeopardize it's maneuverability, power systems or aesthetics, as it needs at least about an 8 x 8 x 9 computer core, and that's still exluding the supporting systems (generators, thrusters for the extra weight, etc.) to go with it.
On the other hand, I just realized that the computer cores under the ship, highlighted in magenta in the picture, are redundant and can be replaced with other systems for a decent boost (~0.4TJ of battery, ~4 GW of power, ~11k additional shields).