Igniter delay and variance can be reduced by increasing the current pushed through them.
The power delivery setup for this launch was probably the most interesting bit. Estes igniters are typically rated to require 2A. Supplying that times 5000 is no simple task. The video seems to show five large boxes (~1m on a side), each surrounded by a cluster of rockets. These boxes probably each concealed a pile of batteries and relays.
