I actually can fit both bottles in there...all 8oz. Don't see the point in buying two bottles when you only use a drop out of the 2nd one. Never hurts to have a little more since it does wear down pretty quick.
Hm, interesting. I probably got like 6.5 ounces in before it got to the threads of the hole... and I was parked on a hill with my rear lower. Of course, you have a different supercharger - is the capacity different between the two?