The good thing about the VF22 is that it's the biggest VF series turbo and cheapest. The bad thing is that it's the slowest VF turbo to spool up (400hp+). If you want mid-top end and don't mind a little bit of lag, this is the turbo to consider. This turbo is also the oldest design. I am going with the VF34 (375hp+) because it spool up faster and it's a newer design...

 

Basically, like wickedrex said, in a nutshell-

Pros- big top end power (if you have good exhaust and fueling)

Cons- lag and high boost threshold

 

how about for an STi? would the extra displacment pic up on the VF22 lag any? I was thinking of a VF34 but not sure if this would be the best upgrade on an STi

 

The VF22 would lag less on the STi than on a WRX, but it wouldn't be a huge improvement over the stock turbo as far as top end.

 

so how would the STi VF 39 compare with the VF30/34? is there any IHI turbo worth upgrading the STi to?