I just hit 2000miles this week on my 2010. So far the biggest bang for my buck has been shifter bushings ($25). Also I picked up a set of sti sways for $125, only put the rear on though, the front sti bar was actually thinner than my stock bar. The car handles much better now, that nasty push is gone and its much more neutral.
I took a ride with a Subaru tech tonight to verify that the hesitation I fell around 4000rpms is normal. I had a feeling it was due to what I have read on the various forums. Funny thing, he said the best thing I could do for the hesitation was a reflash. Not totally suprised to hear this from him, but I was shocked that he offered the info so easily. Of course I played dumb and acted like I don't already have a tactrix cable....
Before I reflash I still have a couple mods to do.
Perrin air filter (sitting in my tool box)
install my synapse reirculated BOV (flange in transit)
install a walbro 255lph pump
I'll probably do a stage1 xpt flash after that.
Then I need to scrape some more cash together for a DP