I got my 125 about 4 months ago. Love it, but always have 135 envy
I will make a few BMW Performance Mods down the track, but at the moment it suits me well as daily driver. Good colour choice BTW.
I agree with most.... get the 135 if you can, but I can confirm you'll be very happy with the 125. I don't know too much about chips, tuning or power upgrades, but if Dazza can provide info on the manifold upgrade, I am sure most 125 owners will snap it up.
Good luck