First off, I don't know much about z32's. With that out of the way, VG's are the devil. You have to yank the motor to do anything on it. haha. IMO the t25's flow enough air. just crank up the boost. If you really want to replace them with something that will flow a tad bit more, 2 big t28's are good as well(not sure about clearance though, sorry).