If it's me, I will upgrade the steering wheel. 316i comes with standard steering, it is thinner, larger and material feel lower grade. So far I have not seen upgrade to the Sport steering on 320i Sport but there seems to be a lot of upgrade to the M Sport steering. One note though, besides the steering, new airbag is required as the standard steering airbag is of different size. Another upgrade is the interior trim, the silver trim that comes with 316i seems to be lower grade as well ...
The rest of the spec, for me, I can leave with it ...