I generally use a dab of threadlock if I'm unsure of the torque settings and ,as you say, just go by feel (que gambit lol)
my 6 speed has the ppp short shift and selection is fine but during "lead foot" I do feel a slight pull on the gearstick when the boost comes in. So I've been looking at the "hardrace" engine and box mounts and various types of bushes and diff braces .