Its probably the earlier on, M2.10.3. The way to tell (I think)is to have a look at your exhaust gas re-circulation system (E.G.R.)
Looking from the front of the car with bonnet up, look at the Throttle butterfly housing. Just under there, by the Thermostat housing you'll find if its M.2.10.3 that there is a funny widget type thigy with pipes that run to the inlet manifold. If its not there its 2.10.4.
If that doesn't make a lot of sense I can take some pictures of both and post them on Monday, as the 155 is .4 and the 145 has .3
Why you asking? You thinking of buying Bug187's squadra chip?