My '09 has an STM, however it came with it when I got it so I can't compare how it feels relative to the OEM one. It's a completely different design/concept though that uses 2 springs, a primary and secondary. One basically controls the force applied on the plates, and the other controls engine braking. Mine had a pretty soft secondary spring so there was very little engine braking available, but never had to worry about rear tire breaking loose. Personally I didn't like that and wanted a bit more engine braking and quicker engagement when I got back on the gas, so I got a new stiffer spring. I think I went with the highest rate they make. Now it's awesome! Just how I like it!
That's a lot of oil changes to switch out the spring isn't it?
Hindle Exhaust(Can), SHOGUN FS, ASV shorty levers, 8000k HID, Renthal C/O, BMC Airfilter.
"It's not about how fast you go, its about how fast you go in a corner"