(G) loss of power in roundabell

Hi there
i have a new fiat punto 1.2 69hp, model:street of 2016 , euro6

I 've read that is lack of power, but i did't image so BIG, expecially during acceleration after roundabell has a loss of power.
-My car dealer said it's normal for new cars for the new ECO restrictions and becuse the engine compared to weight is too small.
-My mechanical suggested to install an additional control unit, then i accepted, he installed a model called "pedalsprint".

The loss of power now is decreased but not resolved, still has some problem on start, hills etc, and this gives a bad driving sensations. It seems perhaps like my car dealer said "the engine compared to weight is too small".
After 3 months of searches i still cannot understand the real problem (if euro6 rescrition or weight) but if it was the weight it seems strange this loss in the roundabell even with the pedal totally down. Yes the additional control unit helped me to solve in part the roundabell problem,perhaps this device does not seems to manage only the RAIL

do you know what is this loss of power in roundabell?
do you suggest to remap the CPU? (it gives just 5HP more)
do you suggesto to buy 1.4 16v model?
do you suggest to buy used euro4 instead euro6?

p.s.
my old car was a fiat punto 55HP euro2, and when i was accelerating it was OK.
NOW ,with 69HP and just 70KG weight more it seems have problems!!