Turbo: STi/WRX VF Series Turbocharger breakdown:
IHI VF37
(430cfm, 250-325whp, Modification Required)
This is the standard equipment turbocharger used on the JDM V8-V9 Subaru Impreza WRX STI. The VF37 is a twin-scroll turbocharger that utilizes a thrust bearing design and a P25 exhaust housing. It is essentially a fast spooling VF30.
Expect to achieve full boost with the proper mods and a quality tune between 2800-3300rpms. 2002-2005 WRX owners will need fuel upgrades for this turbocharger and proper engine management is highly recommended for all vehicles.
IHI VF35
(425cfm, 250-325whp, Bolt-On)
This is the standard equipment turbocharger used on the JDM Subaru Impreza WRX. The VF35 is similar to the VF34. It utilizes the same compressor housing and the same compressor inducer size. The differences are in the divided thrust-bearing design and the P15 exhaust housing.
This allows the VF35 to spool slightly quicker than the VF34 at the cost of less top-end performance.
Expect to achieve full boost with the proper mods and a quality tune between 2800-3300rpms. 2002-2005 WRX owners will need fuel upgrades for this turbocharger and proper engine management is highly recommended for all vehicles.
IHI VF23
(425cfm at 18psi, 250-325whp, Bolt-On)
This is the standard equipment turbocharger used on the JDM Subaru Impreza WRX STi 22b. The VF23 is a ball bearing turbocharger that utilizes the P20 exhaust housing like the VF22. This housing is mated with the smaller compressor housing of the VF24 for fast response and excellent low and mid-range performance. It does not have the same top end power of the VF22, but spools up slightly quicker.
Expect to achieve full boost with the proper mods and a quality tune between 2800-3300rpms. 2002-2005 WRX owners will need fuel upgrades for this turbocharger and proper engine management is highly recommended for all vehicles.