Hot engines? This isn't a TA diesel engine where you can add a 100 HP by doing a ECU program change. A NA engine is really quite limited to what you can hotrod. Timing advance ( I'm sure the're going to run max) it will retard in case of detonation. Any late timing will only increase cylinder temp. The air/fuel mix will or should be running at stoichiometric. Slight changes in injector quantity and duration. In the end, it should hold at 165 hp as advertised. Any more will be a bonus.
there can be porting revisions, pipe changes etc.....they all do it....just like the yamaha putting out over 200hp, it will be turned down also