Stock engine and upgrades. Replace only weapons and ammo. Double RAC5 only are kinda weird and situational: they are best used when pushing / brawling with team mates because they will jam pretty quickly and need some time to unjam. Use this mech as a support mech: move out of cover and keep shooting. Once the bar is filled up, you should already be in the nearbies of the next cover: when the first RAC5 jams, move into cover and wait for the next strafing run, then repeat. Replace AMS with additional ammo if you happen to run out of ammo.