Got this from Clubwrx.net

No info on VF39 but some general info on IHI turbos:

VF22:
This turbo has the highest output potential of all of the IHI VF series turbos and is the best choice for those who are looking for loads of top end power. The top end power however, does not come without a cost. The VF22 spools significantly slower than the rest of the IHI models due to the larger P20 exhaust housing and is much less suited for daily driving than some of the other models. Although the largest VF series turbo, the VF22 is not quite optimal for stroked engines or those who wish to run more than 20PSI of boost. The VF22 is best mated with the 2.0 block and in applications of 20lbs of boost or less.

VF30:
The VF30 is commonly considered the best bang for the buck turbo in the IHI VF series line. A relatively new model the VF30 features the the same exhaust housing as the VF24 but a larger compressor side similar to the VF22. The combination of these two parts results in increased output potential without the lag associated with the VF22. Although it doesn't offer the top end supremecy of the VF22, the VF30 is a great compromise between these unit and the quicker spooling models.

VF34:
The VF34 is nearly identical to the VF30, with the same exhaust housing and compressor. However the VF34 goes back to the ball bearing design, and in doing so achieves full boost approximately 500RPM sooner than the comparable VF30. The VF34 is the most recent IHI design and as such costs slightly more than its counterpart. Top end performance and maximum output are identical to the 30.

Provided by Dark Rex (*Information was derived from many sources including NASIOC, MRT website, PPMotorsports website, clubwrx.net, scoobytech.net, WorldOne and Rallispec website.)

VF23
This turbo is considered a great all-around turbo. Like the VF22 it utilizes the largest P20 exhaust housing. This housing is mated with a smaller compressor housing of the 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 significantly quicker. Standard ball bearing center section. Excellent bolt-on replacement for the standard WRX turbo on cars without any other major modifications. Expect flows around 430 CFM at 18 PSI.


VF24
This turbo shares its compressor housing with the VF23 however, this housing is mated with a smaller (P18) exhaust side. The smaller characteristics of this turbo allow it to provide ample bottom end power and quick spool. This turbo is very popular for Imprezas with automatic transmissions and Group N rally cars. Not recommended for stroker engines or engines with high boost as turbo is small and can over speed. Best turbo for cars that want the best bottom end and least lag. Expect flows around 425 CFM at 18 PSI


VF28
This turbo came standard on the STi Version 5. In terms of overall size, it is smaller than the VF22, VF30 and VF34, and about same size as the VF23. Expect flows around 425 CFM at 18 PSI


VF29
This Turbo is nearly identical to the VF24, with the same compressor and exhaust housings. However the compressor wheel in the VF29 is has been changed slightly. The changes made to the compressor wheel in this model are generally viewed as improvements, and as such this unit is typically chosen over the VF24. Has a different location for the pressure hose on the waste gate actuator Expect flows around 425 CFM at 18 PSI

VF35
The VF35 utilizes the same compressor housing as the VF34 however it also features a divided thrust or offset ball bearing design. The smaller P15 exhaust housing for quicker spool up and a slightly more limited top end. The compressor inducer size is the same as a VF30/or 34 turbocharger.

 

What type comes stock on the WRX?

 

Td-04