As Bitcoin indorse the decentralization I can give my and you can give your opinion on the BIP but where the ultimate results will be processed.
I know the dumb question but clarification is important. As there is no formal voting system so how?
1. The idea is first published on the bitcoin mailing list[1]
2. The idea is discussed by the developers (those who understand the protocol and the code). It could also be discussed elsewhere like this forum.
3. If it is useful, they publish an implementation of it and the testing begins
4. The code can be improved (bug fixes, optimization, etc.) as contributors test the code and report their results and ideas to improve it.
5. The voting mechanism is implemented for the full nodes so that the users can upgrade and miners can vote on it (eg. activate at block X if 95% of previous blocks voted for it)
6. Voting begins and if it reaches the threshold the change is locked in.
[1] https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev