STI-R/A

Hi folks, after a brief fling with a skyline i have decided to keep my ra but i now want more power. I have a full h+s system inc. de-cat + downpipe, and i just added a forge dump valve and its running the standard sti panel filter ( looks pretty old and tatty!) Whats the next step? Im hoping for over 300 bhp what do i need to achieve this??
Regards, Pat.