Ok, I am already hated for my previous post, but I can see that if you are going to service your clutch, yes a flywheel is not stupid. Just don't go too light. It is a real fact that too light is not a good thing. ACT StreetLight or Exedy Stage 2 is acceptable with the power levels you described, avoid RaceLight, or stage 3 anything.

You won't be any more likely to do in your gearbox than to do in the rear differential, if you can get the whole kit at once for a decent price, and you plan to strip and build out those, it may be worth it if you are as sick as me about keeping at it until the car is actually as capable of it's track bred sister STi. If you do one, the other will eat it. Just thought that bore mentioning it, as I had the personal experience with it that many have had... it is painful.