Servo Shuttering
 

So on tank #6 of my new Rc8t RTR my steering servo died. I replaced the high torque (apparently low quality) associated servo with a savox digital high torque.15 speed 20.0 torque servo. The instal was pretty straight forward but when I powered it up I noticed that when the analog throttle servo is under stress the new digital steering servo shutters. The throttle servo is a analog, low torque associated one (the one supplied with the rtr). I noticed it was the worst when at full throttle and full brake. I adjusted the epa (it was rotating a little too far on both throttle and break) on the throttle servo which helped a lot but I still get a small shutter from the steering servo if I apply throttle or break quickly.
Any ideas? Is this normal? Is it because I am using a digital servo with an analog one? Any help will be much appreciated.