Mk8, power upgrade, reinforced structure, internal improvements:

• Added more engines, total power up from 112K to 151K. For now shields up to 1.65 strength with the surplus, will do a complete shield overhaul.
  
• Removed unneeded ammo, total is down to 6400 from 9600. This way the frontal compartment has 6-12 layers of metal before the first ERA armors,
  aimpoint selection will be absolutely miserable with conventional weapons and HEAT both.
  
• Bottom rebuilt from metal-fuel-metal to metal-metal-fuel layers, to take advantage of the armor stacking introduced since the first versions. Even more durable against torpedos.
  
• Buoyancy changes destabilized it quite a bit(rolled up to 10°), dragged center of mass down and updated active stabilization. Max roll allowed is 2°, will stay at ~1°.
  Lowered pitch a little to make the front harder to hit.
  
• Added extra resource storage(total is 1.696m metal, 128K crystal, 416K everything else). Fuel storage upped to 3.36m(40 minutes of combat with the upgraded engines).
  
• Internals cleaned up and reinforced, the nose got a ton of love.

Mk7, laser upgraded and offensive mode added:

• It's now a 35K dps pulsed laser, 22 AP 1 destabilizers. Added 4 fixed combiners each side in the back, +a 2-axis turret on the top that'll only shoot at aerial targets closer than 800m.
  Offensive lasers shut down when hostile missiles are closer than 400m.
  
• Added extra resource storage(total is 1.54m metal, 32K crystal, 384K everything else). Fuel storage upped to 2.815m.
  
• Fixed torpedo targeting, they were accidentally set to use the non-aimpoint channel. They'll also turn upwards a second later, getting cleaner hits on the bottom.
  
• Removed the final repair subvehicle, added a few hundred repair bots.
  
• Shield strength down to 1.2 to give power to the laser.

Mk6, full update phase 1 (weapon refit/power upgrade):

• Max power output up from 75K to 114K.
  
• Railguns replaced, now all 4 turrets use 2x200mm ones. Most recoil absorbers removed and replaced with railgun chargers, total rail energy is much higher but underclocked to 0.5 so final power drain is lower.
  With the high rate of fire and 1000 m/s velocity they are much better against air targets and do more damage to ships, too.
  
• The antispace secondaries replaced with 3 double 2000mm CRAM cannons to brutalize slow targets.
  
• Added a 30rpm, 18mm 3500 m/s max torque gravram railgun in the front. It only shoots at flying targets over 50m altitude, tries to hit the fastest one.
  Does no damage, just tries to get them in the water(where torpedos/CRAMs brutalize them) or in space(where they stall and main railguns murder them).
  
• Torpedos upgraded to 40 m/s 3 fin 2 frag 4 HE, 2x0.9 stagger. They form 2 continuous conga lines, attack from the bottom.
  
• The new railguns murder anything suspectible to sabots, the 16 sabot secondaries reconfigured. Caliber upped to 166mm on all of them, 8 act as CIWS and 8 as HEAT support trying to get ammo/shields.
  
• Leftover power goes to shields, upped from strength 1 to 1.6(a huge buff for inertials).
  
• Preferred range down to 1500m to let the CRAMs murderize things.