Over on the"other" board I was looking at the diagram of the fans, someone posted in your thread. As you can see the PCM, based on the fan settings you can program with a tuner, grounds either the high or low speed circuit to complete the electrical path. If you wanted the fans turning faster you could build a simple voltage regulator circuit and step up the supply voltage to the fan(s) to 16 maybe 18V.
The fans, although turning faster, will still turn on and off based on the PCM settings though. In theory, since they are turning faster and cooling quicker, the time they are on would be reduced.
The larger radiator seems like it would make sense too.
