[KalbiCool88]

Originally Posted by tahdizzle

Gimme a BRZ ts, and I'll slap on a CARB legal Eforce kit and thats a wrap.

You can purchase all the items from the tS now, but its much more convenient to have it from the factory that way for many reasons.
Warranty, Various motorports and classing, laziness (why purchase parts and install them when you can just buy it that way), exclusivity, resale.... many reasons

It's probably even cheaper if you buy it as a package also.