http://forums.nasioc.com/forums/showthread.php?t=1141476 just 1 example: Stock WRX: Mitsubishi TD04L-13T (390cfm at 14.7psi, 200-275whp, Bolt-On) This is the standard equipment turbocharger used on the USDM Subaru Impreza WRX MY02-07. Expect to achieve full boost with the proper mods and a quality tune between 2500-3000rpms. Stock STi 04-06: IHI VF39 (250-325whp, Bolt-On) This is the standard equipment turbocharger used on the USDM Subaru Impreza WRX STI. It can be found on all model years from 2004-2006. The VF39 utilizes a thrust bearing design and the P18 exhaust housing. Expect to achieve full boost with the proper mods and a quality tune between 3000-3500rpms. 2002-2005 WRX owners will need fuel upgrades for this turbocharger and proper engine management is highly recommended for all vehicles that utilize this turbo aftermarket. Though they are prone to cracking, VF39’s can be had for very cheap if bought used.