poncams are good because they use the stock valvetrain.
if you want big power you will need more lift and around 264 duration..
procams are better, but you need to change valve springs, retainers etc
for a stock gtr (internally) cams wont really give too much benifit. ive seen stock cammed gtrs running 600hp with no problems. attend to other parts 1st, such as turbos, ecu, injectors zorst etc