i dunno bout that... bluetwo had some problems when he ordered coilovers... they were designed for an 05 and they wouldnt fit his car if i remember correctly
A change was made in 05 for Sti, but WRX changed in 04. So any 04+ spring should fit the 06. They are slightly longer (if i remember right) than the 02-03. If you have a set in mind and want to be absolutely sure, ask the vendor. A lot of them will give you a straight answer of point you in the right direction.