From the Triumph web site:
A new firing order was incorporated for a more engaged Tiger riding experience giving up to 9% more power across the rev range and a high-overall-peak power of 94 HP @ 8,750 rpm, plus 10% more peak torque than the Tiger 800 predecessor. The Tiger 900’s new T-plane triple crank and new 1,3,2 firing order has improved the character, off-road feel and on road performance of the engine and gives a more aggressive and engaging T-plane triple soundtrack with a more distinctive triple bark.
You get the "soundtrack" and additional vibration at no extra charge!
Seriously, I really, really wanted a Tiger 900, but the new engine just has too much "character" for my liking. Maybe Triumph will tweak it in the future.