The Subaru OEM IHI VF48 turbocharger is a direct bolt-on option for the WRX & STI, utilizing the factory mounting points and attaching to the factory oil and coolant lines. This turbo is a great upgrade option for 2.0L WRX owners looking to make significantly more power and still retain OEM quality and fitment. 2.5L WRX models (2006-2007) will also benefit from a VF48 turbo upgrade, however gains will not be as dramatic as on the 2.0 models as the larger displacement motor will suffer from a taper in power in the high RPM range. STI owners should consider this turbocharger as an OEM replacement only. As with all turbo upgrades, this turbo will require fueling and tuning upgrades to operate safely.
The IHI VF48 comes stock on the 2008+ STI. This turbo has shown to produce numbers of around 300-315whp when tuned aggressively.