cam(s) plus and open up your exhaust ports up some you will see more of a gain than I/H/E
Lot's of ppl don't know you can gain good power by moding your OEM parts such as intake mani and your intake and exhaust ports and a regrind on your cam(s)...bisi does some wonderful things with honda engines..I would look into some of his parts

BTW plz don't be like everyone else and get under drive pulleys either...they just like to eat up main bearings

 

im not familiar w/ the z6.. do you have dpfi or mpfi ? i can hook you up w/ header, an si head, mpfi intake, computer to run the mpfi injection... do you have a 4 speed or a 5 speed? i also have a 5 speed tranny w/ an almost new clutch, i am not able to post pics or i would put this in the for sale section.....
im not on this site very often anymore.... my email is jwsimons2006@yahoo