Had a lot removed, front brace, under car horseshoe brace, air-con etc etc and 5kg FIA seats fitted, WRX is 40-80kg lighter anyway than an STI. I can't help thinking if the WRX had 2 cats and not 3 STI might have had some blushes. I've just removed the pre-cat on the turbo up-pipe and the WRX feels like a totally different animal. They say a good heat-wrapped up-pipe on an STI can give 10bhp and quicker spool so god knows what it gives a WRX.