GEARSHIFTERS

Before each stage you'll be able to choose one of three randomly selected 'Assists'. These assists include cash bonuses, ammo and charge refills, schematics and 'Boosts'. These boosts are usually pretty decent, they provide increases to weapon damage or ammo capacity or some kind of damage reduction etc. They only last for the next stage however then they are removed.

For this achievement you need to activate '15' different boosts, not simply activate any boost 15 times. You'll probably be short 1 or 2 by the end of the campaign but you're able to continue to play afterwards so just clear up any you may have missed by replaying stages.

Below is a checklist of at least 16 boost assists:

1. BOUNTY - Raise value of currency drops by 20%
2. COOLED BARRELS - 50% faster primary weapon cooldown
3. DEFLECTIVE COATING - Reduce any incoming damage by 10%
4. EFFICIENT REPEATER - Increase primary weapon fire rate by 15%
5. EXPANDED CLIP - Increase secondary weapon ammo capacity by 40%
6. FAST LOADER - 50% increase in secondary weapon fire rate
7. FIRE SUPPRESSANT - Prevent repeating damage from fire weapons
8. FOCUSED ROUNDS - Intensify secondary weapon damage by 20%
9. PLASMA GUARD - Reduce damage from energy weapons by 30%
10. PROTECTOR - When integrity is below 50%, incoming damage is 20% lower
11. QUALITY TOOLING - 20% higher primary weapon damage
12. REACTIVE REPAIR - Auto-repair 50% damage if integrity falls below 10%. One use only
13. SCHEMATIC SCANNER - Identify vehicles carrying a schematic
14. SEE AHEAD - Warn of approaching civilian vehicles
15. SHOCK ABSORBER - 30% mitigation of collision damage
16. TREASURE SEEKER - 20% chance of higher level schematic drops

The achievement should unlock as soon as you activate the 15th boost.