Just some FYI. 893 is STOCK for the SVT. If you want the higher watt (50w) fogs they are 885. I picked them up from KarParts for $9.95/each.
They won't damage your wire harness. One of the big differences with them is that they don't have a coated tip on the bulb itself. The 893's use a coated tip which hinders the light. 885's are clear all the way so it lets more light out. It's definitely an easy and cheap upgrade and makes a huge difference. They aren't projector fogs, they are flood fogs, so you won't see a huge difference in distance.