You will need an external vtec kit or go balls out and drill a big ass hole in your block. Use the kit golden eagle. You will need a vtec computer p72 is a gsr. And you will have to wire in vtec 3 wires. Do some research on line its all over the place. I you want get the etm www.hondatech.info

If I was you I would get it tuned. You will have a longer stroke so your engine will pull more air you will probably run a bit lean at WOT.