Well, it ain't no 64hp Fatboy........Interesting it gains 12hp with a mere 100cc bore job and a cam swap. I bet there is more going on - my guess is the stock T-Bird's narrower bore "shouds" the valves a bit. The DRZ400 I own has the same phenomenon - a small bore increase to 435cc on that bike frees up quite a bit of power.
In the end who cares why (except geeks like me). 97hp is pretty darn impressive and meaty. No doubt this chunk of cruiser is a solid and satisfying ride. It is a comparative bargain too.
I looked over a T-Bird in a parking lot. The engine is quite an impressive thing to behold. Liking the twin headlight carryover from the bad boy Speed Triple too. Now that is a bike for me to drool over.
Well played Triumph!