The stock heads have two problems, hydraulic lifters: these will limit the rpm's the engine will be able to operate at = stuck with the 6500rpm limit. If you add the forged pistons/rods your maximum safe rpm limit will be in the 7500 range. Ports: the gentlemen who did the 2.2 turbo airplane engine build discovered insuffecient material around the ports = very limited portability. Because of these two reasons I determined it would be easier to swap in a set of STi heads with there non-hydraulic lifters.
'92 Turbo Legacy
17"SpeedLines/Pzero's (safe in winter storage :-p)