Some advanced/experimental tech specifically says ignore XYZ negative when calculating BV (for example, Void-Signature Systems ignore the heat, or BattleArmor Detachable Weapons Pods ignore the movement modifiers) But modular armor does NOT say ignore the -1 to Walk MP. (which makes sense, because it's not like you can drop it arbitrarily like a weapons pod, or turn it off like the void-signature system.)
However, take the example of the Scorpion Light Tank, Minesweeper version (XTRO Liao page 8, MUL page 50) agree that it has 350 BV. However, the only way to do this is to ignore the Walk MP. (BV breakdown below stolen from MegaMek, with my comments in parentheses to the side)
DBV
Armor: 58 *2.5 = 145 (includes 10 points of modular armor in the FR)
IS: 12*1.5 = 18
Tracked = 0.9 multiplier
Max TMM = 5 = 1.2 Multiplier
DBV = 208.44 (5 and 6 speed has the same TMM, so having the -1 or not does not matter here)
OBV
2xLRM5 = 90
MG = 5
3x LRM5 ammo = 18
1/2 MG ammo = .5
Vehicle tonnage/2 = 12.5
Speed factor = (1 + (6-5)/10)^1.2 = 1.12
OBV = 141.12 (If the Speed Factor was 1 (by including the -1 Walk MP) then the OBV would be 126)
Total = 350 (334 if the -1 Walk MP is included)
So, question - Is the -1 Walk MP for Modular armor included or not in the BV calculations? If so, is there an errata for XTRO Liao and the MUL, and if not, is there an errata for TacOps?
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Edit: Made clear the XTRO is XTRO - Liao
