Originally posted by b16aEGcivic
isnt the 2.5 litre motor in the sti just a boost built 2.5 litre motor from the 2.5RS?
In the simplest terms, sure.
You could also say it's a high boost version of the 2.5 liter turbo motor from the Forester 2.5XT, Baja Turbo and upcoming new Legacy.
Subaru built it to provide the low end torque that would satisfy the tastes of the typical American consumer. It has the added benefit of propelling said Forester to a 13.8 in the 1/4 mile.