Look into getting the IM port matched and reworked. On honda-tech i saw one guy make 15hp just by porting out his type-r manifold. 99si basically covered everything so to sum it up : Cams, header, adjustable cam gears. The piston compression should be fine (JDM is 11.8:1 i think) and u already have 22t water pump and oil pump so u should be ok.