The older Impreza's (2000-2007) are actually pretty small inside to begin with. I wouldn't think making them smaller or shorter would help their sales at all, maybe the two door would, but they just didn't do it. There might have been something in JDM land, but I think they shot for more versatility in those days.
Wait for the Subaru 0846/Toyota FT86. That'll be a little two door with a boxer engine to play with.
If anything look for an older GC 2 door. (90's Impreza/2.5RS) You can find many on the net that are swapped with turbo engines. I think Dougy has one for sale on this forum actually.