Hi akiskaps,Have you activated the MPU6050 on-chip filter? Ideally, it needs to be set at 20Hz.
The MPU6050's Digital Low Pass Filter can be set in its configuration (CONFIG) register.This is detailed on page 13 in the MPU6000 and MPU6050 Register Map Document: https://www.invensense.com/wp-content/uploads/2015/02/MPU-6000-Register-Map1.pdf.
Does anoyone knows any other advice or tip on how to make a perfetly stable drone ?
Perfect, good luck with that.You might want to look into what a Optical Flow sensor or a TOF can do for you in relation to stability of a drone.