I got the short TOR's in large part due to the rampant praise of one said individual /\ /\ above. He was right the sound is perfect and I much prefer the way they look on the bike. I can't comment on if there was a performance change as I picked the bike up at the dealers with them on.
I believe Dazco had the longs on first and was able to notice an performance improvement and a smoothing out of the engine.
Glad I got mine.
I did have the long tors, and them made no noticeable improvement. Later i got the shorts and was very happy and surprised to find they made a huge difference. As big as any pipe could i think. I don't think just a pipe change could give any more than this or it would be unreal. As to the longs, someone else later said thiers DID perform much better, and i looked into it and found mine had a different part # than the new ones do. So i think they changed them, probably due to the performance issue. They have done this in the past often. The tors for the speedy and america has 3 different versions.