?Changes:

Cicada (both models):
Increased to 45 tons
Movement reduced to 6 (Same as Firestarter, Commando)
Melee and DFA damage increased in line with new tonnage (but still a very low melee damage chassis, per tonnage)
25 tons base weight, 20 tons available
Default loadout is 8 tons of armor (640 points)
Hardpoints Modified

Cicada 2A (4E, 2M, 4S)
(Medium Laser x 4, SRM6, 1 SRM Ammo, 4 Heat Sinks)
(Alpha: 148 Damage, 18 Stability)
(Alpha: 54 heat, Sink: 42)

Cicada 3C (4E, 2B, 4S)
(AC/5, 1 AC Ammo, Medium Laser x3)
(Alpha: 120 Damage, 10 Stability)
(Alpha: 40 heat, Sink: 30)

Locust (all models)
Increased to 25 tons
Movement reduced to 7 (Same as Jenner)
Melee/DFA damage increased ?increased in line with new tonnage (but still a low melee damage chassis, per tonnage)
14.5 tons base weight, 10.5 tons available
Default loadout is 4.5 tons of armor (360 points)
Hardpoints of 1V modified

Locust 1M (2E, 2M, 2S)
(LRM5 x2, 1 LRM Ammo, Medium Laser)
(Alpha: 65 Damage, 20 Stability)
(Alpha: 22 heat, Sink: 30)

Locust 1S (1E, 4M, 1S)
(SRM4 x2, 1 SRM Ammo, Medium Laser)
(Alpha: 89 Damage, 24 Stability)
(Alpha: 26 heat, Sink: 30)

Locust 1V (4E, 4S)
(Medium Laser x3, Machine Gun x4, 1 MG Ammo)
(Alpha: 75+60, 0 Stability) *60 MG damage
(Alpha: 30 heat, Sink: 30)

Spider:
Stays 30 tons
Movement speed reduced to 5 (same as Shadowhawk, Griffin, Wolverine, etc)
Head can now mount 45 armor (was 30)
13.5 tons base weight, 16.5 tons available
Default loadout is 7 tons of armor (560 points)
Hardpoints Modified

Spider 5V (4E, 1B, 4S)
(Medium Laser x 4, Jump jets x5, Heat Sinks x 3)
(Alpha: 100 Damage, 0 Stability)
(Alpha: 40 heat, Sink: 39)

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Installation:
Copy everything but backup folder to [...]\BATTLETECH\BattleTech_Data\StreamingAssets\data and overwrite files

Un-install:
Copy everything from backup folder to [...]\BATTLETECH\BattleTech_Data\StreamingAssets\data and overwrite files'

Or

(Steam version): verify integrity of local files