Honestly, I'll be really happy with anything over 300 whp. I realize they're just numbers, but a part of me will feel really proud joining the "300 club" for the first time in my life.
I saw a video of some guy redlining his poor Subaru's engine constantly for several minutes before it finally let go, so I think expecting a well-maintained 300+ whp daily-driven WRX to last well into the 100k's isn't terribly unreasonable. If I can get several more years out of this car without anything major breaking, I'll be incredibly happy.
IAG has a Dynojet 424 AWD in-ground dyno, btw.
17 days and counting...
07 WRX (Albins 5MT + Blouch 20G)
Jorge Carrillo Tuned (365 whp/340 wtq)