I wouldn't worry about pepole believing you mate, if there's an increase on the same rollers and she feels stronger on the old bum-dyno then that's all the proof you need. As long as you're happy yourself at the end of it then that's the main thing. Mine made 193.5BHP & 153.8Ft/lb with just an ITG Panel (197 on ~33,000M at the time), ''book'' figure is 194BHP and she feels strong so that's all the proof I needed.
There's so many variables when it comes to RR figures; fuel, mileage, temperature, dyno make/model, engine/servicing history that when you say you've got X-BHP, you'll always get somebody debating it. A lot of people get caught up with chasing peak figures, there's much more to it then that really. You might only see 10BHP peak but if you've gained 20BHP & 20Ft/lb at 5,500RPM for example then that's one hell of an increase.