The 2.0 comes in 170 bhp as well as 136bhp. The lower power engines may not have the F40 gearbox. One of the flaws of the 2.0 is the poor throttle response in 1st and 2nd gear. It's at its worst when cold, but improves as the engine warms up.
I haven't noticed the poor throttle response on our Giulietta which uses the same engine.
As far as I am aware from here, the 136 and 170 versions of the 159 are different only in terms of engine mapping, so they can both be remapped to around 210 bhp if needed.
Some got the F40 box, some got the C635. The C635 is an OK gearbox, not as strong as the F40- but not as clunky either. An improvement over the M32 none the less.