Over this past weekend, I pulled the motor, removed the heads, and replaced them with a built set of heads with a Brian Crower valvetrain. They were assembled with the 280* cams, stock size stainless valves, and stiffer springs, allowing for an 8500rpm redline. They also received a small port job on both ends. Although I don't have a proper tune yet (Aug. 8th), the difference in the engine was as incredible as it was quiet, and the power was almost instant. I never knew a set of cams and valvetrain could make such a difference. A sound clip for your enjoyment: http://www.youtube.com/watch?v=EhEBpz2xlsU
Haven't had it tuned yet, but it idles ok right now at about 8-900 rpm. I don't think the bottom end can spin that high, so I'll likely keep it around the 7200-7500 mark.
WHats the weak link on the WRX bottom end with regards to high rpm speeds. O nthe EVO the max you want to go is 8000. Rod bolts are the weakest link at that point.