CTR pistons actually "stick out" higher than regular pistons from a b16. When you calculate the compression ratio, you actually have to factor in a lower deck height (.000) to compensate. If you just plug in the numbers, you get 10.8:1. However, the compression is actually 11.4:1 with an OEM headgasket. With the flat face valves, you're looking at a 11.5-11.7 compression ratio.

With the already high dome height of the PCT pistons, I would definitely not mill the head at all.