I just wanted to say that the graph from the first page doesn't make any sense to me. I don't know where those numbers are gotten from but that just seems like an excel sheet replica from a bunch of numbers. peak horsepower at 4800rpm? Are you kidding me? I have lots of NA dyno graphs both i-avls and non-avls that present a much broader power range (hp 5600-6000rpm and torque 2500-5000rpm). I think overall subaru did a good job tuning the 2.5l sohc engines...from most dynos over 95% of peak torque is made at only 2500rpm. There is however the infamous subaru torque dip at 3500rpm, which i have no idea what causes it. But you can see this dip in almost every NA subaru engine...i'm suspecting the intake manifold. There is also a general lack of torque below 2000rpm, pretty bad for uphills from a standstill. but it's fine once it climbs pass that threshold.
+08 2.5i (second gen AVLS)
07-06 2.5i (first gen AVLS)
2.5 rs (Non AVLS) blue is stock - lack of low end is because of open loop delay.
some stuff can be concluded from the 2.5l sohc...firstly they all suffer from open loop delay problems, meaning car stays lean until past 4k rpm. this can be fixed with an ecu reflash on most models. Another is the dip at 3.5k rpm and below 2k rpm. On a hot humid day, climbing a hill with my A/C on from a standstill can be embarrassing in the 2.5i. Overall though it is fairy well tuned the streets with a broad power range between 2500-5000rpm, but i guess you all already knew this! Here is a 2.4l Toyota 4 banger for comparison, notice how torque is almost non existent below 3.5k rpm on those camrys:
2.4l toyota blue is stock