I recently resurrected my '97 Impreza Brighton with mostly Legacy parts and the rear struts, springs and mounts from an '04 WRX. In order to make the struts fit I had to slot two of the three strut mount holes a bit, in the body, on each side. I'm sure some of you are cringing and truth be told it made me more than a little nervous to do it but the results were worth it.
Yesterday I received the front struts, springs and mounts from an '05 STi and yet again modifications were in order to make them fit. Apparently the STi spindle is about 1/8" wider than the Legacy spindles that are currently on the Brighton and the spindle-to-strut bolt holes are spread about 3/8" further apart. Luckily I am a packrat and still had two non-cam strut bolts from the Legacy.
I took a few measurements, layed out the tool path the best I could, by hand, in my driveway then set to work with a rotary file mounted in a die-grinder. From center to center the new hole is down 3/8" and in 1/8" from the original upper hole in the strut flange which is just enough to pop a straight strut bolt through and securely mount it to a first gen. Legacy or GC Impreza spindle. Camber is no longer adjustable due to the use of two straight bolts and the absolute lack of any slop whatsoever but I don't mind. I used flat washers to fill the gap between the spindle and strut flange but I will be making a shim soon.
The added front stiffness makes the old Scoob feel like a precision instrument and it is MUCH more balanced now. With the blown Legacy front struts with rusty springs and the like-new WRX rears it tended toward oversteer in all situations which, to me, feels strange in a Subaru. Now it's what I assume a normally aspirated, haggard 22B would feel like.
Just figured I would share. By far this was the best $100 upgrade I have ever put on a car!