HeyLostOblivion, I did a quick experiment, I have used the same RM-105-45 RCS thrusters as you, and put them on a rocket that approximates yours. The problem is the Mini thrusters have not enough thrust to roll the rocket quickly, during pitch and yaw the thrusters are far away from the center of mass, this means they have a long lever. For roll however the only half the diameter of your fuel tank can be used as leverage, to test this I also put a second set of RM-105-45 thrusters on booms (5 cubic octagonal struts). I got the following results for a 60° turn in seconds. Stock RCS: 7 RM-105-45: 22 On boom Stock RCS: 2 RM-105-45: 6 So you could use more RCS thrusters or put them further away from the central axis. P.s. Sorry if that sounds confusing English is not my first language.