Thinking that more ports is faster is wrong. Going out from only Novarossi models the 7 ports models are commercially slower made so the more expensive 9 port engine must be the best to get.
Most other brands have max 7 ports and there is nothing wrong with them. Regarding your GRP/Ninja, if all parts are box stock then there is a lot of room to get more out of it. They are out of the box nice engines but do need some tuning to compete with the best Novarossi, Sirio and Picco models.