Get under the car and check the water pump weep hole. It's a small hole where the shaft of the water pump goes into the body of the pump. It's most likely leaking from there but not so much that it leaevs any puddles.

I had one on my 00 for over six months before it was figured out. Dealership had it on the lift for a clutch change and noticed there was just enough antifreeze coming from teh weep hole to lose it but not enough to hit the ground before it evaported. I opted to swap the pump myself and bingo, no more fluid loss.

 

yeah. youre probably not going to see it but im pretty sure you have a leak somewhere. just try it man, Im telling u i went to the dealership a thousand times and they werent even able to find it but it definetly was there. you can also try checking the temp. with youre sct or diablosport i was running at about 209 210 most likely that small leak was causing air bubbles to run through the coolant system. new radiator problem fixed