Originally Posted by RoboTuner
The 16 STi is twin scroll and uses EL headers, so you won't see the true gains that turbo supports without EL headers and the rest of the TS setup.
thats the WRX using the FA20. the STI still uses the EJ25 and is not twin scroll.
Originally Posted by Ruso
If the turbo bolts right on, which I'm fairly certain it does.
the turbo bolts right in yes and fits fine, its the connection between the Y-pipe and the compressor housing that will be off a few MM...
i cant find the picture of the VF 48 comparison but here are the twin scroll versions...
left is a VF37 on a Cable Throttle motors, right is the VF52 on Drive By Wire motors
notice the compressor housing outlet on the right in bent a little bit. this is to clear the DBW throttle assembly. you'll notice the same few degrees of bend in the pic ruso linked above. its only a few millimeters, but that will matter when you are trying to wiggle on your intercooler, and im quite certain the plastic wrx y-pipe will crack trying to fit it on thus resulting in boost leaks
other than that, everything else works fine.
the turbo will get you to 300ish wheel hp, but not with just turbo + injectors + intercooler. i should have stated that sorry. yes with more mods you can see a total gain of 100whp over stock using a VF turbo on your WRX.
the reason you dont hear about this issue much is because most people when upgrading to a VF turbo, upgrade to an STI intercooler, thus never encountering the problem to begin with. personally, i have never heard of anyone using a VF turbo and not getting an STI intercooler at bare minimum.