Stephen,
The CAI was something that i wanted to get when i was aiming for the 350mark. The drilled and removable fogger with the tumble dryer hose aiming in near the filter doesnt make much of a difference, practically nothing. will help more cold air in but only keeping the chargetemp better for a few more seconds.
Your choice at the end of the day. I know some of the WRX's that are over or near to 300 have them so maybe speak to someone like Bing or Irish Al and see what they think.