The Clutch in my 2001 WRX is slipping and getting worse,I'll be replacing the Clutch very soon and was going to upgrade to a lightened flywheel at the same time.

What I need to know is,how light is too light?, one I was looking at is a Billet Chromoly and weighs only 4.5 kg. I see most are at around 6kg,the car is my daily driver and a fair bit of stop start traffic going to and coming home from work.I have read on some forums that going too light can cause CEL Codes??.

also, out of interest what does the standard 2001 wrx flywheel weigh

any advice much appreciated