How can I find out which OBs can be turned into a bigger HP?

[cptlook]

Hi, new but learning - how can I find out which motors can be turned into a bigger HP? I've heard the 9.9s can be turned into a 15. Is that 4 strokes & 2 strokes? How do I find out which motors can be upgraded? Thanks for any help.

 

[boscoe]

By comparing parts in the Yamaha parts catalogs.

 

[cptlook]

Ok, thanks