That 4G is beast. I used to own a 2G Eclipse GSX. I knew a decent amount of guys that did impressive things with the Mitsus, and I'm talking about the old school DSM motor. These newer motors, shiiiiiieeet forget about it. I still got love for the 4G63.
I actually like all three camps. The SR is probably easier to work with in this application since it comes RWD. Also probably lighter than the 4G since it's all aluminum. This thing is kinda cool, but I think he could have made a real serious car keeping it all Subaru. Going with a inline four messes up the advantage in engine placement he had when the boxer was in there. Those GC8s were plenty light with awd and that turbo boxer.
If it was me I'd get it up to maybe like 300awhp. That's definitely doable with the EJ20. Then I'd try to make the car as badass as the best Sti versions that were put out. I'd try to do some lightening of the car too.
Props for doing something different but I think for the time and money spent I think his car would have been more bad ass going all Subaru and keeping the awd. My perspective is more slanted to track driving though. Maybe this guy is more into getting sideways.