shift kit or vb upgrade

what up everyone i am pretty new around here but i just got my maxima a lil bit ago right now its in the shop because it was leaking tranny fluid like it was taking a piss but anywaze it is under warrenty. but what i wanted to know was i have a slush boz tranny, and was wondering were i can find a shift kit for my 93 max but i don't know if upgrading the VB would also help or both would be good for my auto. thanks for the feedback!!!!!!!!!!!!!!!!