b16 trannys are going to be shorter geared than gsr trannys. my favorite tranny set up, and my future plan when I need to rebuild mine, is a gsr with an ls 5th gear. longer gears from 1st to 4th than a b16, and the ls 5th gear will keep rpms low on the highway. good luck finding a gsr tranny with ls 5th already in it, but sometimes you get lucky.