I'm SO glad I've kept mine stock, except for a minimally wider tire than what it came with, since I always felt it looked just a bit under-tired.
In any case, since the Honda engineers felt the car was fairly maximized for everyday and track use by the factory, and I like to keep a special car like the 'R' stock, I've left it alone and am glad. Of course, I don't race it, -though I am near some great back roads for spirited driving, and use them frequently - . and haven't had it on a track, which I'd love to do.
To me, being an older guy, my '98 is flashy enough and fun enough, and I don't care for a louder exhaust or turbo-lag, or anything that might interfere with the car's everyday reliability.
Sometimes I play with the idea of some subtle cosmetics in the interior or a nice mesh grill for the large intake in front but haven't done it yet. It's fast enough, and fun enough as it is, for me at least. If I had a regular Integra or Civic I'd probably do a lot of modifying.
The bottom line is: just enjoy your special car, no matter WHAT you do to it!