l already have a small spoiler for my 2007 Subaru wrx sedan (not STI)....but l was wondering can l replace the small wing for the big STl wing on the back of my whip?.......if l cant why not?

of course. the ST l still has the same rear end (trunk) as the standard WRX, so of course it will fit

It fits. Of course, you will have to drill holes as the mounting holes are not the same. The easiest way is to try Nasioc and find someone to do a trunk lid swap. This way you will get a stock STi trunk lid and not have to do any drilling.

of course it fits perfectly

it takes a lot more than you think. l am getting ready to to a trunk lid swap from my 05 rs to a 05 STi, and to do so requires that the back seat be taken out, and the trunk lid springs be swapped. the wing on the STi is heavier than that on a WRX. it will look good in the end but it will take a few hours. for more info on it, and to find someone who wants to trade lids, check out RS25.com

try asking subaru to swich the wing standard for a ST l insted