Take a look at some of the 8 related stuff on this site.

Engine upgrade stages, including porting and what looks and from google could translate as being a modified greddy/trust turbo kit.

http://revo-tune.jp/catalogue/list.p...ve_w=RX-8(SE3P)

And then this cool little battery relocation kit that goes in the washer fluid holder spot. The cool thing about it is that you can also get a washer fluid tank attatchment and a catch can attatchment.

http://revo-tune.jp/catalogue/detail.php?id=24

There are other things like an ecu upgrade and things like that aswell. I recommend using your favorite translator and checking this site out.