Your description of the front becoming spongy sounds like an oil issue to me. Admittedly, I don't know much about dirt bike setup, but my experience with other suspension would say that your oil is either getting too hot or it's foaming. Maybe try a different oil. I'm going to switch to Ohlins when I get around to picking some up. I know a race tech valve kit exists for the forks, but I'm going to play with oil first.
I hadn't seen the race tech G3 for the rear. Is that a valve kit, or is it a whole shock?