What would parts would I need to change to the 06 set up. And does any body offer a kit for this? Do the stock 02 rotors work for this?
Or I'm looking for a direct replacement for the stock calipers, but using the stock rotors.

 

https://www.subarugenuineparts.com/a...=4-pot&x=0&y=0

I hope the above link works.

You can use the stock '02 WRX rotors with either the red (2006 WRX) or black 4-pot front calipers but if you are using stock WRX rims, the calipers won't clear the wheels.

I have a new set of black 4-pots that I will be installing in the coming weeks on my early '02 WRX. I am using 16" x 7" 2000 - 2001 Impreza 2.5 RS wheels which have enough clearance for the 4-pots.

The rear '06 2-pot installation is more involved than installing the front calipers. There are some other kits on the market that use either larger Subaru rear rotors or aftermarket units, along with brackets that reposition the OEM rear caliper to work with the larger rotor.

EDIT: There is a 4-pot installation tutorial at ScoobyMods.com (you have to be a registered member to view the pics).