I just finished installing Pioneer component speakers for the 02 WRX sedan. Although I haven't installed the tweeters yet, I believe stock tweeter is sufficient enough for my liking.
What you need:
- 3M double sided tape $3.50
- Hair dryer~
- Spacer kit to fit woofer so that it won't interfere with window operation: http://www.iaperformance.com/index.asp
- speaker wires