what year miata cams can fit in the 1.8 dohc head?and what kinda gains am i going to see. and does anybody know if the pistons are different in the miata then the protege. and if there is increased hp for swaping them out.

 

please read this and click on the links:

www.members.aol.com/solomiata/MX5Engine.html

also:

www.members.aol.com/solomiata/street.html

 

All year Miatas with the 1.8l engine will work. Your best bet would be the 99+ cams, but you'll need the solid lifters as well. Gains?? I don't know. I'm planning on getting them myself but haven't really had the opportunity to get down to the dealership while the parts department is open.
The pistons should also fit, they are higher compression in the later models