If the SA, PAS & ADC are fitted as standard, then they shouldn't occupy optional internal slots. These three systems, one might argue, are more than likely just software based and wouldn't require any physical hardware in order for them to function. So, I think it would be a good idea to make them so that they are just part of the software and don't require internal slots, with the option of disabling them in the systems panel. That would free up three internal slots that could be much better utilised for something else. Yes, we can currently get rid of them, but if they're installed by default anyway, then surely it's given that they shouldn't take up optional internal slots?