Engine swaps and air bag suspension

[deadboy]

Sorry, but I can tell you for sure, that this stuff won't get added. It's not NFS likely to have airbags animated and working. It's a useless detail and would bring only lags.
If you mean air suspension like changing the height of your right, then this is planned and will be probably (not sure) be part of the planned "Dyno-Tuning Update", but it will take a while until this update will get started to work on, because the development-team of this server is really small and they are busy with URL (Underground Racing League) at the moment.

Engine swaps won't get accepted as suggestion because it shouldn't be possible to drive class E cars with better engines (just as an example). Hardly to imagine how the ranking system would work then.