To me it was a HUGE difference. There is no more bang for the buck you could possibly do to the bike. Almost 30% more power and torque. I loved my bike, just wanted more oomph, especially starting off 2 up. It's like a whole different bike and I can't even tell the difference when my wife rides. It cost me a total of $1200. including labor. I would have paid way more than that for an optional more powerful version from Triumph.
The exhaust even sounds better as it is now slightly lower pitched. There's not a bike in the Triumph line I would rather have right now - including the newer models. I was considering the new mystery mid sized cruiser, but not anymore. I don't really want a radiator in front of my "classic" cruiser.