co2/HPA bulk tank, increases vlocity and ammount you can shoot
mod board, make it unlimited burst (30rd clip) instead of 1,3,or 6 rd and increases max ROF from 600rpm to 1200
solenoid adjustment, increases velocity more
and thats about it, a fully moded drozd can shoot 1200 rounds/min at close to 600fps with a hpa tank, goes through a full 30 round clip in less than 2 seconds

its accurate too, within 3 iches at about 20-30 foot, and even more so with extended barrel and bulk air. ive heard about people using compress helium to get velocities close to 800fps
