[Racing Rice]

Originally posted by SVT Cobra
wrx= 2.0 with turbo
sti = 2.5 with turbo

...only advantage sti really has is the displacement...

Not really...

First off, its 2.5-liter turbocharged engine is rated at 300 horsepower and 300 pound-feet of torque. It's connected to a six-speed manual transmission that sends the power through an all-wheel-drive system fortified with DCCD (Driver Control Center Differential). The DCCD system allows the driver to manually select the front-to-rear torque bias or merely set it in automatic mode and let the computer do the work. Further on down the line, the STi is upgraded with an electronically controlled limited-slip differential in front and a mechanically actuated limited slip in the rear. The car sits almost half an inch lower than the standard WRX and features aluminum control arms, inverted struts and a quicker steering ratio. The wheels are 17-by-7.5-inch BBS aluminum alloys wrapped in supersticky Z-rated 225/45R17 Bridgestone Potenza RE070 directional tires. The brake system was upgraded with four piston Brembo calipers in front and two piston versions in back along with an Electronic Brakeforce Distribution system and a Super Sport Antilock system that controls lock up on individual wheels according to lateral G-forces.

The interior of the STi gets a laundry list of changes as well. The seats are upgraded with heavier side-bolstering integrated headrests and unique blue Ecsaine fabric. Since weight is the enemy of speed, the STi banished the stereo system to the options sheet and swapped in lightweight rear window glass. The STi specific instrument cluster includes a 9,000-rpm tachometer, 160-mph speedometer and DCCD display to go along with the standard temp and fuel gauges. There's also a driver-selectable shift light so you'll never get so caught up in the power that you forget to grab the next gear.

From Edmunds.com


There are many changes to the STi.. If this is accurate..