i'm not 100% on aus spec cars as i've read several different kerb weights for different dc2 models, but there is 27lbs in it between the US gsr (vtir) and type-r. i'd bet you could blame the stupid-arse sunroof for a good portion of that too. so assuming the case is the same in australia, a gsi sans sunroof must be awfully close to the itr in terms of kerb weight.
and fwiw -> the lsd is the main reason i only mentioned turn in and adjustability in my original post.