I don't think the limit is tuning... it needs cams, and possibly head work, to get it breathing up top. Getting this engine to breathe above ~7k rpm is the key to higher hp. Look at any non FI dyno and they all fall off at the same point.
If you can keep the torque curve flat to 8000rpm (150wtq), that's 230whp. No amount of tuning is going to do that without cams.
