SiKid86

I've looked but havn't found a solid anwser on this.. At what hp range does not having a port/polish job on a b16 start to mess with the air flow? I know the greddy turbo kits are capable of producing 300whp, but what is the area of max hp the 18g will produce? And I am assuming that if i wanted a bigger turbo I could just get like a 20g or somthing so I wouldn't have to change out the mani and turbo. Thanks for the help in advance.