nielsk wrote:

Can't find anything about it but is the use of active PSI sleights a mental action? Would be nice if someone could direct me to the passage in the book where this stands. I ask because I am wondering you could use Multi-Tasking in combat for doing something like shooting with one complex action and activate two active PSI sleight with the other available complex mental actions. I somehow hope that using PSI sleights aren't mental actions ;)

Yes they are. All psi skills are mental skills (page 176), which means that using those skills is a mental action (as is all sleights). Granted, certain aspects of psi are not mental skills... like the touch attacks required for certain psi gamma sleights. You may use those sleights if you are in contact with someone already, but cannot make the touch attack that normally is allowed when using such sleights. Do remember, however, that there is still strain involved when using active sleights. It may sound like a huge advantage to be able to use many sleights in a single turn, but they will also be taking a large amount of strain damage in every turn as well.