I have no idea about the later VF stuff above 37- on wrx so feel free to comment if you have real world exp. Ive run VF22/23/28/36 in P18 and 20 housings so drawing most of this from personal real world exp. BIt of a mess but easiest way to blurt it out read and weep. The common early single scroll turbos are like so from biggest to smallest roughly. BB VF22, BB 23, BB 34/ Journal 30, Journal VF35, BB 24/28/29. The 24/28/29 are all pretty much identical not worth changing from one to the oth