I haven't read anything about any changes in the differentials for the 09 model. For the prodrive modified one there was mention of one though, but that's a different car. The exhaust also is not the SPT exhaust and is more of a supporting mod given the larger turbo. They increased the size of the turbo, so changes in the exhaust are pretty much mandatory. The premium package included more than just an aero kit. Heated seats, heated mirrors, wiper defrosters, 6-disk cd-changer. The new addition to the premium package is the sun-roof/moon-roof. There is still a premium package for the 09 wrx. The price listed here is the starting price without the premium package, not the loaded price.my understanding is, it is the full meal deal w/ center lsd, larger turbo, prem pkg, suspension, stitching and spt exhaust all as standard.