The additional relays are one of the best methods for speeding up the windows. The reason is there is incredible amounts of resistance through the window switches, resulting in only 8 volts reaching the windows. It seems the power drop is in the line from the switch, going to the doors. The extra relays relieve the current from the switches, so you get the full 12 volts at the motor.
I haven't done this since greasing and cleaning pulleys and new cable worked fine on my GT4. Slower than a modern car, but much better than originally.