assuming from your screen name that you have an EK, well if you get the longer GSR radiator then you have to remove the condensor for the AC. You could get away with a nice thick delsol dual core radiator. If you get any oem units try to get some end tanks that can be welded to the core of the radiator. I had a oem unit GSR radiator on my b16 and after a little while idling it blew, so I went out and bought a used GSR radiator that had brass end tanks welded to the core, never a problem since.
Milan