I am currently stacking Animal Stak2 with Shock Therapy/Storm.
I like it so far,the Animal Stak2 seems to give me extra energy and drive,I take it before a workout with the Shock Therapy,get some awesome pumps and can slam the reps like crazy.
After I'm done with the Stak 2,I'm gonna be trying the M-Stak,and might stack them both together later on.