The paper gives an overview of several types of signatures sequences for communication in CDMA systems with more users than the spreading factor. We contrast the maximum allowable number of users with turbo detection for a range of scalable and non-scalable sequence sets in synchronous CDMA systems. In addition, we examine how the maximum acceptable system load can be increased in these systems by displacing the sequences of the users with respect to each other. Finally, we also evaluate the downlink user capacity of these sequences sets, and discuss some upper bounds on the user capacity both for systems with synchronized sequences and for systems with sequences that are displaced to one another.