Probably got the wrong forum for this one but here we go anyway

For those of you with longboards and longboard style 666 boards ( must be a couple of you hiding out there ) do you use the same size fins in both .
My longboard 666 has a 9 inch centre with 4 inch side bites , goes pretty good . Wondering if I go same as my longboards with 7 inch centers and 4 inch side bites will performance improve , or am I waisting my time , not to mention money , considering the 666 already has extra turning power in the paddle and is a deeper and wider board .