Multiecuscan

Is it possible to add a feature for bypassing the seat airbags and seat belt chime on the USA version of the Fiat 500 for those people that replace their stock seats with racing seats that do not have airbags in them?

I do not think that is so simple...
You must understand few things abut airbag control units (in general):
- in a small chip inside of airbag unit is a software for those side and seat airbags.
- on the airbag unit you have connectors for those side and seat airbags.
- you have installations, cables and connectors for those side and seat airbags.
- and so on...

It is such amount of work for this thing....

You can do something very simple and it cost you a little bit of time and maximum 1 USD.
Install simulator and that is it!