The type R's are generally pretty quick and good handling cars anyway. It may get expensive trying to improve on this.
But for starters you could replace the airfilter with an aftermarket one with cold air feed. Fit a custom exhaust from manifold all the way through to the rear can. Ditch the cat. And fit a de-cat pipe. After those you could get it remapped and i'm sure you will be very happy with the results. You could also look into front and rear strut braces to keep things nice and tight through the twisties.
That should keep you going for a while.