No they won’t harm your electrical system at all. While vehicle electrical systems are usually referred to as 12VDC, there is actually quite a bit of fluctuation, depending on the output of the alternator or stator. Most voltage regulators in vehicles will pass more than the nominal voltage, so as to do things like charge the battery while driving. Watts, voltage and amperage are all inter-related as described by Ohm’s law, where Power (watts) = Intensity (amperage) x Electromotive force (voltage). So in theory, in order to produce 55W of light, your stock bulbs require 12V, and will draw about 4.5A, while the replacement bulbs at 12.8V will only draw about 4.3A for the same 55W of light. Of course, no vehicle I have ever owned produced exactly 12V, so the amount of light being produced is actually dependent on the resistance in the bulb, which is an unspecified value...