In 2007, a number of small changes were made to the US-spec model. Due to Subaru’s decision to reduce costs by cutting the amount of aluminum used, the US-spec STI no longer receives the J-spec Spec C control arms. The control arms are now the aluminum control arms used on the Japan-spec revision A and B non-Spec C STis. The high caster angle has been reduced, which in turn reduces the wheelbase from 100″ to 99.4″.
The rear swaybar has decreased in size from 20mm to 19mm. The gear ratios of second, third and fourth gears have been made longer (higher ratio) in order to improve fuel economy and driveability, which inadvertently reduces 1/4 miles drag racing times due to the ability to trap 114 mph in 4th gear, without the shift to 5th. The EJ257′s cylinder heads have been redesigned to improve cooling, and the sodium-filled exhaust valves have been deleted.
The alternator is changed from a 90A rating to 110 amps. The rear LSD is now a Torsen unit, considered an upgrade over the previous model’s helical unit. The turbo has also been changed to the VF43, which has a slightly larger wastegate than the VF39.
The side cowl braces are stiffer than the 2006MY. The engine mounts are once again the hard rubber mounts used prior to 2006. On the interior, there is an audio jack that replaces the ashtray, a rear center armrest with trunk pass-through and a 120W audio system.The WRX STI Limited
is introduced. It is similar to the Japan-spec STI A-line, except the mechanicals of the car are based on the 2007MY US-spec WRX STI.