I personally feel that the GR2s aren't any better than stock struts. I've ridden in an SHO with them, and I feel that they are an excellent alternative for someone who needs to replace the stock struts, or who wants a compliment for lowering springs, but as far as performance I feel they offer almost no gain. Some might say they do, but I think this might be more of a case of replacing old worn struts with some good new parts than an actual performance increase of any sort. I think if you want to make the most of your car's handling, Tokicos or Konis are a must. There have ben a plethra of topics about performance struts as of recently, check back in this section and you will find a ton of good info.
Start with the suspension and brakes. IMO, if I had it to do all over again, I'd go with the suspension and leave the engine dead stock for quite a while. The car is powerful man, and if it's running great stock, leave it that way for a while. How about some nice, wide 16s or 17s with good rubber, a set of SFCs, good springs and struts, and a better sway bar setup. I think you will have much more fun bustin' around turns than you will spending $1000 to see a 7hp improvment. Just the opinion of a "modification veteran."